Provided by: libmail-box-perl_2.110-1_all bug

NAME

       Mail::Box - manage a mailbox, a folder with messages

INHERITANCE

        Mail::Box
          is a Mail::Reporter

        Mail::Box is extended by
          Mail::Box::Dir
          Mail::Box::File
          Mail::Box::Net

SYNOPSIS

        use Mail::Box::Manager;
        my $mgr    = Mail::Box::Manager->new;
        my $folder = $mgr->open(folder => $ENV{MAIL}, ...);
        print $folder->name;

        # Get the first message.
        print $folder->message(0);

        # Delete the third message
        $folder->message(3)->delete;

        # Get the number of messages in scalar context.
        my $emails = $folder->messages;

        # Iterate over the messages.
        foreach ($folder->messages) {...} # all messages
        foreach (@$folder) {...}          # all messages

        $folder->addMessage(Mail::Box::Message->new(...));

       Tied-interface:

        tie my(@inbox), 'Mail::Box::Tie::ARRAY', $inbox;

        # Four times the same:
        $inbox[3]->print;                 # tied
        $folder->[3]->print;              # overloaded folder
        $folder->message(3)->print;       # usual
        print $folder->[3];               # overloaded message

        tie my(%inbox), 'Mail::Box::Tie::HASH', $inbox;

        # Twice times the same
        $inbox{$msgid}->print;            # tied
        $folder->messageId($msgid)->print;# usual

DESCRIPTION

       A Mail::Box::Manager creates "Mail::Box" objects.  But you already knew, because you started with the
       Mail::Box-Overview manual page.  That page is obligatory reading, sorry!

       "Mail::Box" is the base class for accessing various types of mailboxes (folders) in a uniform manner.
       The various folder types vary on how they store their messages, but when some effort those differences
       could be hidden behind a general API. For example, some folders store many messages in one single file,
       where other store each message in a separate file withing the same directory.

       No object in your program will be of type "Mail::Box": it is only used as base class for the real folder
       types.  "Mail::Box" is extended by

       See documentation in the base class.

OVERLOADED

       overload: ""()
           (stringification)  The  folder  objects  stringify  to  their name.  This simplifies especially print
           statements and sorting a lot.

           example: use overloaded folder as string

            # Three lines with overloading: resp. cmp, @{}, and ""
            foreach my $folder (sort @folders)
            {   my $msgcount = @$folder;
                print "$folder contains $msgcount messages\n";
            }

       overload: @{}()
           When the folder is used as if it is a reference  to  an  array,  it  will  show  the  messages,  like
           messages() and message() would do.

           example: use overloaded folder as array

            my $msg = $folder->[3];
            my $msg = $folder->message(3);          # same

            foreach my $msg (@$folder) ...
            foreach my $msg ($folder->messages) ... # same

       overload: cmp()
           (string comparison) folders are compared based on their name.  The sort rules are those of the build-
           in "cmp".

METHODS

       See documentation in the base class.

   Constructors
       See documentation in the base class.

       Mail::Box->new(OPTIONS)
           Open a new folder. A list of labeled OPTIONS for the mailbox can be supplied. Some options pertain to
           Mail::Box, and others are added by sub-classes.

           To  control delay-loading of messages, as well the headers as the bodies, a set of *_type options are
           available. "extract" determines whether we want delay-loading.

            -Option           --Defined in     --Default
             access                              'r'
             body_delayed_type                   Mail::Message::Body::Delayed
             body_type                           <folder specific>
             coerce_options                      []
             create                              <false>
             extract                             10240
             field_type                          undef
             fix_headers                         <false>
             folder                              $ENV{MAIL}
             folderdir                           undef
             head_delayed_type                   Mail::Message::Head::Delayed
             head_type                           Mail::Message::Head::Complete
             keep_dups                           <false>
             lock_file                           undef
             lock_timeout                        1 hour
             lock_type                           Mail::Box::Locker::DotLock
             lock_wait                           10 seconds
             locker                              undef
             log                Mail::Reporter   'WARNINGS'
             manager                             undef
             message_type                        <folder-class>::Message
             multipart_type                      Mail::Message::Body::Multipart
             remove_when_empty                   <true>
             save_on_exit                        <true>
             trace              Mail::Reporter   'WARNINGS'
             trusted                             <depends on folder location>

           access => MODE
             Access-rights to the folder.  Folders are opened for read-only  (which  means  write-protected)  by
             default! MODE can be

             'r': read-only (default)
             'a': append
             'rw': read-write
             'd': delete

             These  MODE has no relation to the modes actually used to open the folder files within this module.
             For instance, if you specify "rw", and open the folder, only read permission on the folder-file  is
             required.

             Be  warned: writing a MBOX folder may create a new file to replace the old folder.  The permissions
             and owner of the file may get changed by this.

           body_delayed_type => CLASS
             The bodies which are delayed: which will be read from file when it is needed, but not before.

           body_type => CLASS|CODE
             When messages are read from a folder-file, the headers will be stored in a "head_type" object.  For
             the body,  however,  there  is  a  range  of  choices  about  type,  which  are  all  described  in
             Mail::Message::Body.

             Specify  a  CODE-reference which produces the body-type to be created, or a CLASS of the body which
             is used when the body is not a multipart or nested.  In  case  of  a  code  reference,  the  header
             structure is passed as first argument to the routine.

             Do  not  return a delayed body-type (like "::Delayed"), because that is determined by the "extract"
             option while the folder is opened.  Even delayed message will require some real body type when they
             get parsed eventually.  Multiparts and nested messages are also outside your control.

             For instance:

              $mgr->open('InBox', body_type => \&which_body);

              sub which_body($) {
                  my $head = shift;
                  my $size = $head->guessBodySize || 0;
                  my $type = $size > 100000 ? 'File' : 'Lines';
                  "Mail::Message::Body::$type";
              }

             The   default   depends   on   the   mail-folder   type,   although   the   general   default    is
             Mail::Message::Body::Lines.  Please check the applicable manual pages.

           coerce_options => ARRAY
             Keep  configuration  information  for  messages  which  are coerced into the specified folder type,
             starting with a different folder type (or even no folder at all).  Messages which are  coerced  are
             always fully read, so this kind of information does not need to be kept here.

           create => BOOLEAN
             Automatically  create  the  folder  when it does not exist yet.  This will only work when access is
             granted for writing or appending to the folder.

             Be careful: you may create a different folder type than you expect unless  you  explicitly  specify
             Mail::Box::Manager::open(type).

           extract => INTEGER | CODE | METHOD | 'LAZY'|'ALWAYS'
             Defines  when to parse (process) the content of the message.  When the header of a message is read,
             you may want to postpone the reading of the body: header information is more often needed than  the
             body  data,  so  why parse it always together?  The cost of delaying is not too high, and with some
             luck you may never need parsing the body.

             If you supply an INTEGER to this option, bodies of those messages with a total size less than  that
             number  will  be  extracted  from  the folder only when necessary.  Messages where the size (in the
             "Content-Length" field) is not included in the header, like  often  the  case  for  multiparts  and
             nested messages, will not be extracted by default.

             If  you supply a CODE reference, that subroutine is called every time that the extraction mechanism
             wants to determine whether to parse the body or not. The subroutine is called  with  the  following
             arguments:

              CODE->(FOLDER, HEAD)

             where   FOLDER   is   a   reference   to   the   folder   we  are  reading.   HEAD  refers  to  the
             Mail::Message::Head::Complete head of the message at hand.  The routine must return a "true"  value
             (extract  now)  or  a  "false"  value  (be  lazy,  do  not  parse  yet).   Think  about  using  the
             Mail::Message::Head::guessBodySize() and Mail::Message::guessTimestamp() on the header to determine
             your choice.

             The third possibility is to specify the NAME of a method.   In  that  case,  for  each  message  is
             called:

              FOLDER->NAME(HEAD)

             Where each component has the same meaning as described above.

             The  fourth  way  to  use this option involves constants: with "LAZY" all messages will be delayed.
             With "ALWAYS" you enforce unconditional parsing, no delaying will take place.  The latter is usuful
             when you are sure you always need all the messages in the folder.

              $folder->new(extract => 'LAZY');  # Very lazy
              $folder->new(extract => 10000);   # Less than 10kB

              # same, but implemented yourself
              $folder->new(extract => &large);
              sub large($) {
                 my ($f, $head) = @_;
                 my $size = $head->guessBodySize;
                 defined $size ? $size < 10000 : 1
              };

              # method call by name, useful for Mail::Box
              # extensions. The example selects all messages
              # sent by you to be loaded without delay.
              # Other messages will be delayed.
              $folder->new(extract => 'sent_by_me');
              sub Mail::Box::send_by_me($) {
                  my ($self, $header) = @_;
                  $header->get('from') =~ m/\bmy\@example.com\b/i;
              }

           field_type => CLASS
             The type of the fields to be used in a header. Must extend Mail::Message::Field.

           fix_headers => BOOLEAN
             Broken MIME headers usually stop the parser: all lines not parsed are added  to  the  body  of  the
             message.   With this flag set, the erroneous line is added to the previous header field and parsing
             is continued.  See Mail::Box::Parser::Perl::new(fix_header_errors).

           folder => FOLDERNAME
             Which folder to open (for reading or writing). When used for reading (the "access"  option  set  to
             "r"  or  "a")  the  mailbox should already exist and must be readable. The file or directory of the
             mailbox need not exist if it is opened for reading and writing ("rw").  Write-permission is checked
             when opening an existing mailbox.

             The folder name can be preceded by a "=", to indicate that it is named relative  to  the  directory
             specified in new(folderdir).  Otherwise, it is taken as relative or absolute path.

           folderdir => DIRECTORY
             Where  are  folders to be found by default?  A folder-name may be preceded by a equals-sign ("=", a
             "mutt" convension) to explicitly state that the folder is located below the default directory.  For
             example: in case "folderdir => '/tmp'" and "folder => '=abc'",  the  name  of  the  folder-file  is
             '/tmp/abc'.  Each folder type has already some default set.

           head_delayed_type => CLASS
             The headers which are delayed: which will be read from file when it is needed, but not before.

           head_type => CLASS
             The    type    of    header    which    contains    all    header    information.     Must   extend
             Mail::Message::Head::Complete.

           keep_dups => BOOLEAN
             Indicates whether or not duplicate messages within the folder should be  retained.   A  message  is
             considered  to  be  a duplicate if its message-id is the same as a previously parsed message within
             the same folder. If this option is false (the default) such  messages  are  automatically  deleted,
             because it is considered useless to store the same message twice.

           lock_file => FILENAME
             The name of the file which is used to lock.  This must be specified when locking is to be used.

           lock_timeout => SECONDS
             When  the lock file is older than the specified number of SECONDS, it is considered a mistake.  The
             original lock is released, and accepted for this folder.

           lock_type => CLASS|STRING|ARRAY
             The  type  of  the  locker  object.   This  may  be  the  full  name  of  a  CLASS  which   extends
             Mail::Box::Locker,  or one of the known locker types "DotLock", "Flock", "Mutt", "NFS", "POSIX", or
             "NONE".  If an ARRAY is specified, then a Multi locker is built which uses the specified list.

           lock_wait => SECONDS
             SECONDS to wait before failing on opening this folder.

           locker => OBJECT
             An OBJECT which extends Mail::Box::Locker, and will handle folder  locking  replacing  the  default
             lock behavior.

           log => LEVEL
           manager => MANAGER
             A reference to the object which manages this folder -- typically an Mail::Box::Manager instance.

           message_type => CLASS
             What  kind  of  message objects are stored in this type of folder.  The default is constructed from
             the folder class followed by "::Message".  For instance, the message type for "Mail::Box::POP3"  is
             "Mail::Box::POP3::Message"

           multipart_type => CLASS
             The default type of objects which are to be created for multipart message bodies.

           remove_when_empty => BOOLEAN
             Determines whether to remove the folder file or directory automatically when the write would result
             in a folder without messages nor sub-folders.

           save_on_exit => BOOLEAN
             Sets  the  policy  for  saving  the folder when it is closed.  A folder can be closed manually (see
             close()) or in a number of implicit ways, including on the moment the program is terminated.

           trace => LEVEL
           trusted => BOOLEAN
             Flags whether to trust the data in the folder or not.  Folders which  reside  in  your  "folderdir"
             will  be trusted by default (even when the names if not specified staring with "=").  Folders which
             are outside the folderdir or read from STDIN (Mail::Message::Construct::read()) are not  trused  by
             default, and require some extra checking.

             If  you do not check encodings of received messages, you may print binary data to the screen, which
             is a security risk.

   The folder
       $obj->addMessage(MESSAGE, OPTIONS)
           Add a message to the folder.  A message  is  usually  a  Mail::Box::Message  object  or  a  sub-class
           thereof.   The message shall not be in an other folder, when you use this method.  In case it is, use
           Mail::Box::Manager::moveMessage() or Mail::Box::Manager::copyMessage() via the manager.

           Messages with id's which already exist in this folder are not added.

           BE WARNED that message labels may get lost when a message is moved from one folder type to an  other.
           An  attempt  is  made  to  translate  labels,  but  there  are  many differences in interpretation by
           applications.

            -Option--Default
             share   <not used>

           share => BOOLEAN
             Try to share the physical resource of the current  message  with  the  indicated  message.   It  is
             sometimes  possible  to  share  messages  between  different folder types.  When the sharing is not
             possible, than this option is simply ignored.

             Sharing the resource is quite dangerous, and only available for a limited number of  folder  types,
             at  the  moment  only  some Mail::Box::Dir folders; these file-based messages can be hardlinked (on
             platforms that support it).  The link may get broken when one message is modified  in  one  of  the
             folders.... but maybe not, depending on the folder types involved.

           example:

            $folder->addMessage($msg);
            $folder->addMessages($msg1, $msg2, ...);

       $obj->addMessages(MESSAGE [, MESSAGE, ...])
           Adds  a  set of MESSAGE objects to the open folder at once.  For some folder types this may be faster
           than adding them one at a time.

           example:

            $folder->addMessages($msg1, $msg2, ...);

       Mail::Box->appendMessages(OPTIONS)
           Append one or more  messages  to  an  unopened  folder.   Usually,  this  method  is  called  by  the
           Mail::Box::Manager::appendMessage(), in which case the correctness of the folder type is checked.

           For  some  folder  types it is required to open the folder before it can be used for appending.  This
           can be fast, but this can also be very slow (depends on the implementation).  All OPTIONS passed will
           also be used to open the folder, if needed.

            -Option  --Default
             folder    <required>
             message   undef
             messages  undef
             share     <false>

           folder => FOLDERNAME
             The name of the folder to which the messages are to be appended.  The  folder  implementation  will
             avoid opening the folder when possible, because this is resource consuming.

           message => MESSAGE
           messages => ARRAY-OF-MESSAGES
             One  reference  to a MESSAGE or a reference to an ARRAY of MESSAGEs, which may be of any type.  The
             messages will be first coerced into the correct message type to fit in the folder, and then will be
             added to it.

           share => BOOLEAN
             Try to share physical storage of the message.  Only available for a limited number of folder types,
             otherwise no-op.

           example:

            my $message = Mail::Message->new(...);
            Mail::Box::Mbox->appendMessages
             ( folder    => '=xyz'
             , message   => $message
             , folderdir => $ENV{FOLDERS}
             );

           better:

            my Mail::Box::Manager $mgr;
            $mgr->appendMessages($message, folder => '=xyz');

       $obj->close(OPTIONS)
           Close the folder, which usually implies writing the changes.  This will return "false"  when  writing
           is required but fails.  Please do check this result.

           WARNING:  When  moving  messages  from one folder to another, be sure to write the destination folder
           before writing and closing the source folder.  Otherwise you may lose data if the system  crashes  or
           if there are software problems.

            -Option      --Default
             force         <false>
             save_deleted  false
             write         MODIFIED

           force => BOOLEAN
             Override  the  new(access) setting which was specified when the folder was opened. This option only
             has an effect if its value is TRUE. NOTE: Writing to  the  folder  may  not  be  permitted  by  the
             operating system, in which case even "force" will not help.

           save_deleted => BOOLEAN
             Do also write messages which where flagged to be deleted to their folder.  The flag for deletion is
             conserved  (when  possible),  which  means that a re-open of the folder may remove the messages for
             real.  See write(save_deleted).

           write => 'ALWAYS'|'NEVER'|'MODIFIED'
             Specifies whether the folder should be written.  As could be expected, "ALWAYS" means always  (even
             if  there  are  no  changes), "NEVER" means that changes to the folder will be lost, and "MODIFIED"
             only saves the folder if there are any changes.

           example:

            my $f = $mgr->open('spam', access => 'rw')
                or die "Cannot open spam: $!\n";

            $f->message(0)->delete
                if $f->messages;

            $f->close
                or die "Couldn't write $f: $!\n";

       $obj->copyTo(FOLDER, OPTIONS)
           Copy the folder's messages to a new folder.  The new folder may be of a different type.

            -Option       --Default
             delete_copied  <false>
             select         'ACTIVE'
             share          <not used>
             subfolders     <folder type dependent>

           delete_copied => BOOLEAN
             Flag the messages from the source folder to be deleted, just after it  was  copied.   The  deletion
             will only take effect when the originating folder is closed.

           select => 'ACTIVE'|'DELETED'|'ALL'|LABEL|!LABEL|FILTER
             Which messages are to be copied. See the description of messages() about how this works.

           share => BOOLEAN
             Try  to  share  the message between the folders.  Some Mail::Box::Dir folder types do support it by
             creating a hardlink (on UNIX/Linux).

           subfolders => BOOLEAN|'FLATTEN'|'RECURSE'
             How to handle sub-folders.  When false (0  or  "undef"),  sub-folders  are  simply  ignored.   With
             "FLATTEN",  messages  from sub-folders are included in the main copy.  "RECURSE" recursively copies
             the sub-folders as well.  By default, when the destination folder supports sub-folders "RECURSE" is
             used, otherwise "FLATTEN".  A value of true will select the default.

           example:

            my $mgr  = Mail::Box::Manager->new;
            my $imap = $mgr->open(type => 'imap', host => ...);
            my $mh   = $mgr->open(type => 'mh', folder => '/tmp/mh',
                create => 1, access => 'w');

            $imap->copyTo($mh, delete_copied => 1);
            $mh->close; $imap->close;

       $obj->delete(OPTIONS)
           Remove the specified folder file or folder directory (depending on the type of folder) from disk.  Of
           course, THIS IS DANGEROUS: you "may" lose data.  Returns a "true" value on success.

           WARNING: When moving messages from one folder to another, be sure to  write  the  destination  folder
           before deleting the source folder.  Otherwise you may lose data if the system crashes or if there are
           software problems.

            -Option   --Default
             recursive  1

           recursive => BOOLEAN

           example: removing an open folder

            my $folder = Mail::Box::Mbox->new(folder => 'InBox', access => 'rw');
            ... some other code ...
            $folder->delete;

           example: removing an closed folder

            my $folder = Mail::Box::Mbox->new(folder => 'INBOX', access => 'd');
            $folder->delete;

       $obj->folderdir([DIRECTORY])
           Get or set the DIRECTORY which is used to store mail-folders by default.

           example:

            print $folder->folderdir;
            $folder->folderdir("$ENV{HOME}/nsmail");

       $obj->name()
           Returns the name of the folder.  What the name represents depends on the actual type of mailbox used.

           example:

            print $folder->name;
            print "$folder";       # overloaded stringification

       $obj->organization()
           Returns how the folder is organized: as one "FILE" with many messages, a "DIRECTORY" with one message
           per file, or by a "REMOTE" server.

       $obj->size()
           Returns  the  size  of  the  folder in bytes, not counting in the deleted messages.  The error in the
           presented result may be as large as 10%, because the in-memory  representation  of  messages  is  not
           always the same as the size when they are written.

       $obj->type()
           Returns a name for the type of mail box.  This can be "mbox", "mh", "maildir", or "pop3".

       $obj->update(OPTIONS)
           Read new messages from the folder, which where received after opening it. This is quite dangerous and
           shouldn't be possible: folders which are open are locked. However, some applications do not use locks
           or the wrong kind of locks. This method reads the changes (not always failsafe) and incorporates them
           in the open folder administration.

           The  OPTIONS  are  extra  values  which  are passed to the updateMessages() method which is doing the
           actual work here.

       $obj->url()
           Represent the folder as a URL (Universal Resource Locator) string.  You may pass such a URL as folder
           name to Mail::Box::Manager::open().

           example:

            print $folder->url;
            # may result in
            #   mbox:/var/mail/markov   or
            #   pop3://user:password@pop.aol.com:101

   Folder flags
       $obj->access()
           Returns the access mode of the folder, as set by new(access)

       $obj->isModified()
           Checks if the folder, as stored in memory, is modified.  A true value is returned  when  any  of  the
           messages is to be deleted, has changed, or messages were added after the folder was read from file.

           WARNING: this flag is not related to an external change to the folder structure on disk.  Have a look
           at update() for that.

       $obj->modified([BOOLEAN])
           Sets whether the folder is modified or not.

       $obj->writable()
           Checks whether the current folder is writable.

           example:

            $folder->addMessage($msg) if $folder->writable;

   The messages
       $obj->current([NUMBER|MESSAGE|MESSAGE-ID])
           Some  mail-readers  keep  the  current  message, which represents the last used message.  This method
           returns [after setting] the current message.  You may specify a NUMBER, to specify that that  message
           number is to be selected as current, or a MESSAGE/MESSAGE-ID (as long as you are sure that the header
           is already loaded, otherwise they are not recognized).

           example:

            $folder->current(0);
            $folder->current($message);

       $obj->find(MESSAGE-ID)
           Like messageId(), this method searches for a message with the MESSAGE-ID, returning the corresponding
           message  object.   However,  "find"  will cause unparsed message in the folder to be parsed until the
           message-id is found.  The folder will be scanned back to front.

       $obj->findFirstLabeled(LABEL, [BOOLEAN, [ARRAY-OF-MSGS]])
           Find the first message which has this LABEL with the correct setting. The BOOLEAN  indicates  whether
           any  true value or any false value is to be found.  By default, a true value is searched for.  When a
           message does not have the requested label, it is taken as false.

           example: looking for a labeled message

            my $current = $folder->findFirstLabeled('current');

            my $first   = $folder->findFirstLabeled(seen => 0);

            my $last    = $folder->findFirstLabeled(seen => 0,
                            [ reverse $self->messages('ACTIVE') ] )

       $obj->message(INDEX [,MESSAGE])
           Get or set a message with on a certain index.  Messages which are flagged for deletion  are  counted.
           Negative indexes start at the end of the folder.

           example:

            my $msg = $folder->message(3);
            $folder->message(3)->delete;   # status changes to `deleted'
            $folder->message(3, $msg);
            print $folder->message(-1);    # last message.

       $obj->messageId(MESSAGE-ID [,MESSAGE])
           With one argument, returns the message in the folder with the specified MESSAGE-ID. If a reference to
           a  message  object  is  passed  as  the  optional second argument, the message is first stored in the
           folder, replacing any existing message whose message ID is MESSAGE-ID. (The  message  ID  of  MESSAGE
           need not match MESSAGE-ID.)

           !!WARNING!!:  when  the  message headers are delay-parsed, the message might be in the folder but not
           yet parsed into memory. In this case, use find() instead  of  "messageId()"  if  you  really  need  a
           thorough search.  This is especially the case for directory organized folders without special indexi,
           like Mail::Box::MH.

           The  MESSAGE-ID  may  still  be in angles, which will be stripped.  In that case blanks (which origin
           from header line folding) are removed too.  Other info around the angles will be removed too.

           example:

            my $msg = $folder->messageId('<complex-message.id>');
            $folder->messageId("<complex-message\n.id>", $msg);
            my $msg = $folder->messageId('complex-message.id');
            my $msg = $folder->messageId('garbage <complex-message.id> trash');

       $obj->messageIds()
           Returns a list of all message-ids in the folder, including those of messages which are to be deleted.

           For some folder-types (like MH), this method may cause all  message-files  to  be  read.   See  their
           respective manual pages.

           example:

            foreach my $id ($folder->messageIds) {
               $folder->messageId($id)->print;
            }

       $obj->messages(['ALL',RANGE,'ACTIVE','DELETED',LABEL,!LABEL,FILTER])
           Returns  multiple  messages  from  the  folder.   The default is "ALL" which will return (as expected
           maybe) all the messages in the folder.  The "ACTIVE" flag will return the messages  not  flagged  for
           deletion.   This  is the opposite of "DELETED", which returns all messages from the folder which will
           be deleted when the folder is closed.

           You may also specify a RANGE: two numbers specifying begin and end index in the  array  of  messages.
           Negative  indexes count from the end of the folder.  When an index is out-of-range, the returned list
           will be shorter without complaints.

           Everything else than the predefined names is seen as labels.  The messages which have that label  set
           will  be  returned.   When  the  sequence  starts  with an exclamation mark (!), the search result is
           reversed.

           For more complex searches, you can specify a FILTER, which is simply a code reference.   The  message
           is passed as only argument.

           example:

            foreach my $message ($folder->messages) {...}
            foreach my $message (@$folder) {...}

            # twice the same
            my @messages   = $folder->messages;
            my @messages   = $folder->messages('ALL');

            # Selection based on a range (begin, end)
            my $subset     = $folder->messages(10,-8);

            # twice the same:
            my @not_deleted= grep {not $_->isDeleted}
                                $folder->messages;
            my @not_deleted= $folder->messages('ACTIVE');

            # scalar context the number of messages
            my $nr_of_msgs = $folder->messages;

            # third message, via overloading
            $folder->[2];

            # Selection based on labels
            $mgr->moveMessages($spam, $inbox->message('spam'));
            $mgr->moveMessages($archive, $inbox->message('seen'));

       $obj->nrMessages(OPTIONS)
           Simply  calls  messages()  in  scalar context to return a count instead of the messages itself.  Some
           people seem to understand this better.  Note that nrMessages() will default to returning a  count  of
           "ALL" messages in the folder, including both "ACTIVE" and "DELETED".

           The OPTIONS are passed to (and explained in) messages().

       $obj->scanForMessages(MESSAGE, MESSAGE-IDS, TIMESPAN, WINDOW)
           You  start  with  a  MESSAGE,  and  are  looking  for a set of messages which are related to it.  For
           instance, messages which appear in the 'In-Reply-To' and 'Reference' header fields of  that  message.
           These messages are known by their MESSAGE-IDS and you want to find them in the folder.

           When  all  message-ids  are known, then looking-up messages is simple: they are found in a plain hash
           using messageId().  But Mail::Box is lazy where it can, so many messages may not have been read  from
           file yet, and that's the preferred situation, because that saves time and memory.

           It  is  not  smart  to search for the messages from front to back in the folder: the chances are much
           higher that related message reside closely to each other.  Therefore, this method starts scanning the
           folder from the specified MESSAGE, back to the front of the folder.

           The TIMESPAN can be used to terminate the search based on the time enclosed in the message.  When the
           constant string "EVER" is used as TIMESPAN, then the search is not limited by that.  When an  integer
           is  specified,  it will be used as absolute time in time-ticks as provided by your platform dependent
           "time" function.  In other cases, it is passed to timespan2seconds() to determine  the  threshold  as
           time relative to the message's time.

           The  WINDOW  is  used  to limit the search in number of messages to be scanned as integer or constant
           string "ALL".

           Returned are the message-ids which were not found during the scan.  Be warned that a message-id could
           already be known and therefore not found: check that first.

           example: scanning through a folder for a message

            my $refs   = $msg->get('References') or return;
            my @msgids = $ref =~ m/\<([^>]+\>/g;
            my @failed = $folder->scanForMessages($msg, \@msgids, '3 days', 50);

   Sub-folders
       $obj->listSubFolders(OPTIONS)
       Mail::Box->listSubFolders(OPTIONS)
           List the names of all sub-folders to this folder, not recursively  decending.   Use  these  names  as
           argument to openSubFolder(), to get access to that folder.

           For MBOX folders, sub-folders are simulated.

            -Option    --Default
             check       <false>
             folder      <from calling object>
             folderdir   <from folder>
             skip_empty  <false>

           check => BOOLEAN
             Should  all  returned foldernames be checked to be sure that they are of the right type?  Each sub-
             folder may need to be opened to check this, with a folder type dependent  penalty  (in  some  cases
             very expensive).

           folder => FOLDERNAME
             The folder whose sub-folders should be listed.

           folderdir => DIRECTORY
           skip_empty => BOOL
             Shall  empty  folders  (folders  which  currently  do not contain any messages) be included?  Empty
             folders are not useful to open, but may be useful to save to.

           example:

            my $folder = $mgr->open('=in/new');
            my @subs = $folder->listSubFolders;

            my @subs = Mail::Box::Mbox->listSubFolders(folder => '=in/new');
            my @subs = Mail::Box::Mbox->listSubFolders; # toplevel folders.

       $obj->nameOfSubFolder(SUBNAME, [PARENTNAME])
       Mail::Box->nameOfSubFolder(SUBNAME, [PARENTNAME])
           Returns the constructed name of the folder with NAME, which is a sub-folder of this current one.  You
           have either to call this method as instance method, or specify a PARENTNAME.

           example: how to get the name of a subfolder

            my $sub = Mail::Box::Mbox->nameOfSubfolder('xyz', 'abc');
            print $sub;                        # abc/xyz

            my $f = Mail::Box::Mbox->new(folder => 'abc');
            print $f->nameOfSubfolder('xyz');  # abc/xyz

            my $sub = Mail::Box::Mbox->nameOfSubfolder('xyz', undef);
            print $sub;                        # xyz

       $obj->openRelatedFolder(OPTIONS)
           Open a folder (usually a sub-folder) with the same options as this one.  If there is a folder manager
           in use, it will be informed about this new folder.  OPTIONS overrule the options which where used for
           the folder this method is called upon.

       $obj->openSubFolder(SUBNAME, OPTIONS)
           Open (or create, if it does not exist yet) a new subfolder in an existing folder.

           example:

            my $folder = Mail::Box::Mbox->new(folder => '=Inbox');
            my $sub    = $folder->openSubFolder('read');

       $obj->topFolderWithMessages()
       Mail::Box->topFolderWithMessages()
           Some folder types can have messages in the top-level folder, some other can't.

   Internals
       $obj->coerce(MESSAGE, OPTIONS)
           Coerce the MESSAGE to be of  the  correct  type  to  be  placed  in  the  folder.   You  can  specify
           Mail::Internet  and  MIME::Entity  objects  here: they will be translated into Mail::Message messages
           first.

       $obj->create(FOLDERNAME, OPTIONS)
       Mail::Box->create(FOLDERNAME, OPTIONS)
           Create a folder.  If the folder already exists, it will be left unchanged.  The  folder  is  created,
           but   not   opened!   If  you  want  to  open  a  file  which  may  need  to  be  created,  then  use
           Mail::Box::Manager::open() with the create flag, or Mail::Box::new(create).

            -Option   --Default
             folderdir  undef

           folderdir => DIRECTORY
             When the foldername is preceded by a "=", the "folderdir" directory will be searched for the  named
             folder.

       $obj->determineBodyType(MESSAGE, HEAD)
           Determine which kind of body will be created for this message when reading the folder initially.

       Mail::Box->foundIn([FOLDERNAME], OPTIONS)
           Determine if the specified folder is of the type handled by the folder class. This method is extended
           by each folder sub-type.

           The  FOLDERNAME  specifies  the  name of the folder, as is specified by the application.  You need to
           specified the "folder" option when you skip this first argument.

           OPTIONS is a list of extra information for the request.  Read the  documentation  for  each  type  of
           folder for type specific options, but each folder class will at least support the "folderdir" option:

            -Option   --Default
             folderdir  undef

           folderdir => DIRECTORY
             The  location  where the folders of this class are stored by default.  If the user specifies a name
             starting with a "=", that indicates that the folder is to be found in this default DIRECTORY.

           example:

            Mail::Box::Mbox->foundIn('=markov',
                folderdir => "$ENV{HOME}/Mail");
            Mail::Box::MH->foundIn(folder => '=markov');

       $obj->lineSeparator([STRING|'CR'|'LF'|'CRLF'])
           Returns the character or characters used to separate lines  in  the  folder  file,  optionally  after
           setting it to STRING, or one of the constants.  The first line of the folder sets the default.

           UNIX  uses  a  LF  character,  Mac  a  CR,  and  Windows  both a CR and a LF.  Each separator will be
           represented by a "\n" within your  program.   However,  when  processing  platform  foreign  folders,
           complications appear.  Think about the "Size" field in the header.

           When the separator is changed, the whole folder me be rewritten.  Although, that may not be required.

       $obj->locker()
           Returns the locking object.

       $obj->read(OPTIONS)
           Read  messages  from  the folder into memory.  The OPTIONS are folder specific.  Do not call "read()"
           yourself: it will be called for you when you open the folder via the manager or instantiate a  folder
           object directly.

           NOTE: if you are copying messages from one folder to another, use addMessages() instead of "read()".

           example:

            my $mgr = Mail::Box::Manager->new;
            my $folder = $mgr->open('InBox');             # implies read
            my $folder = Mail::Box::Mbox->new(folder => 'Inbox'); # same

       $obj->readMessages(OPTIONS)
           Called  by  read() to actually read the messages from one specific folder type.  The read() organizes
           the general activities.

           The OPTIONS  are  "trusted",  "head_type",  "field_type",  "message_type",  "body_delayed_type",  and
           "head_delayed_type" as defined by the folder at hand.  The defaults are the constructor defaults (see
           new()).

       $obj->storeMessage(MESSAGE)
           Store the message in the folder without the checks as performed by addMessage().

       $obj->toBeThreaded(MESSAGES)
           The  specified  message  is  ready  to be removed from a thread.  This will be passed on to the mail-
           manager, which keeps an overview on which thread-detection objects are floating around.

       $obj->toBeUnthreaded(MESSAGES)
           The specified message is ready to be included in a thread.  This will  be  passed  on  to  the  mail-
           manager, which keeps an overview on which thread-detection objects are floating around.

       $obj->updateMessages(OPTIONS)
           Called  by  update()  to  read  messages which arrived in the folder after it was opened.  Sometimes,
           external applications dump messages in a folder without locking (or using a different lock than  your
           application does).

           Although  this  is  quite  a  dangerous, it only fails when a folder is updated (reordered or message
           removed) at exactly the same time as new messages arrive.  These collisions are sparse.

           The options are the same as for readMessages().

       $obj->write(OPTIONS)
           Write the data to disk.  The folder (a "true" value) is returned if successful.  Deleted messages are
           transformed into destroyed messages: their memory is freed.

           WARNING: When moving messages from one  folder  to  another,  be  sure  to  write  (or  close())  the
           destination  folder before writing (or closing) the source folder: otherwise you may lose data if the
           system crashes or if there are software problems.

           To write a folder to a different file, you must  first  create  a  new  folder,  then  move  all  the
           messages, and then write or close() that new folder.

            -Option      --Default
             force         <false>
             save_deleted  <false>

           force => BOOLEAN
             Override  write-protection  with  new(access)  while  opening the folder (whenever possible, it may
             still be blocked by the operating system).

           save_deleted => BOOLEAN
             Do also write messages which where flagged to be deleted to their folder.  The flag for deletion is
             conserved (when possible), which means that a re-open of the folder may  remove  the  messages  for
             real.  See close(save_deleted).

       $obj->writeMessages(OPTIONS)
           Called  by  write()  to  actually  write  the  messages  from  one specific folder type.  The "write"
           organizes the general activities.  All options to write() are  passed  to  "writeMessages"  as  well.
           Besides, a few extra are added by "write" itself.

            -Option  --Default
             messages  <required>

           messages => ARRAY
             The messages to be written, which is a sub-set of all messages in the current folder.

   Other methods
       $obj->timespan2seconds(TIME)
       Mail::Box->timespan2seconds(TIME)
           TIME  is  a  string,  which  starts  with  a float, and then one of the words 'hour', 'hours', 'day',
           'days', 'week', or 'weeks'.  For instance: '1 hour' or '4 weeks'.

   Error handling
       See documentation in the base class.

       $obj->AUTOLOAD()
           See "Error handling" in Mail::Reporter

       $obj->addReport(OBJECT)
           See "Error handling" in Mail::Reporter

       $obj->defaultTrace([LEVEL]|[LOGLEVEL, TRACELEVEL]|[LEVEL, CALLBACK])
       Mail::Box->defaultTrace([LEVEL]|[LOGLEVEL, TRACELEVEL]|[LEVEL, CALLBACK])
           See "Error handling" in Mail::Reporter

       $obj->errors()
           See "Error handling" in Mail::Reporter

       $obj->log([LEVEL [,STRINGS]])
       Mail::Box->log([LEVEL [,STRINGS]])
           See "Error handling" in Mail::Reporter

       $obj->logPriority(LEVEL)
       Mail::Box->logPriority(LEVEL)
           See "Error handling" in Mail::Reporter

       $obj->logSettings()
           See "Error handling" in Mail::Reporter

       $obj->notImplemented()
           See "Error handling" in Mail::Reporter

       $obj->report([LEVEL])
           See "Error handling" in Mail::Reporter

       $obj->reportAll([LEVEL])
           See "Error handling" in Mail::Reporter

       $obj->trace([LEVEL])
           See "Error handling" in Mail::Reporter

       $obj->warnings()
           See "Error handling" in Mail::Reporter

   Cleanup
       See documentation in the base class.

       $obj->DESTROY()
           This method is called by Perl when an folder-object is no  longer  accessible  by  the  rest  of  the
           program.

DETAILS

   Different kinds of folders
       In  general,  there  are  three  classes  of  folders: those who group messages per file, those who group
       messages in a directory, and those do not provide direct access to the message data.  These folder  types
       are each based on a different base class.

       •   File based folders Mail::Box::File

           File  based  folders maintain a folder (a set of messages) in one single file.  The advantage is that
           your folder has only one single file to access, which speeds-up things  when  all  messages  must  be
           accessed at once.

           One  of  the main disadvantages over directory based folders is that you have to construct some means
           to keep all message apart.  For instance MBOX adds a message separator line between the  messages  in
           the file, and this line can cause confusion with the message's contents.

           Where  access  to all messages at once is faster in file based folders, access to a single message is
           (much) slower, because the whole folder must be read.  However, in directory based folders  you  have
           to figure-out which message you need, which may be a hassle as well.

           Examples of file based folders are MBOX, DBX, and NetScape.

       •   Directory based folders Mail::Box::Dir

           In  stead  of  collecting  multiple messages in one file, you can also put each message in a separate
           file and collect those files in a directory to represent a folder.

           The main disadvantages of these folders are the enormous amount of tiny files you usually get in your
           file-system.  It is extremely slow to search through your whole folder, because many files have to be
           opened to do so.

           The best feature of this organization is that each message is kept exactly as it  was  received,  and
           can be processed with external scripts as well: you do not need any mail user agent (MUA).

           Examples of directoy organized folders are MH, Maildir, EMH, and XMH.

       •   Network (external) folders Mail::Box::Net

           Where  both  types  described before provide direct access to the message data, maintain these folder
           types the message data for you: you have to request for messages or parts of them.  These folders  do
           not  have a filename, file-system privileges and system locking to worry about, but typically require
           a hostname, folder and message IDs, and authorization.

           Examples of these folder types are the popular POP and IMAP, and database oriented message storage.

   Available folder types
       •   Mail::Box::Dbx (read only)

           Dbx files are created by Outlook Express. Using the external (optional) Mail::Transport::Dbx  module,
           you can read these folders, even when you are running MailBox on a UNIX/Linux platform.

           Writing  and  deleting  messages  is not supported by the library, and therefore not by MailBox. Read
           access is enough to do folder conversions, for instance.

       •   Mail::Box::IMAP4 (partially)

           The IMAP protocol is very complex.  Some parts are implemented to  create  (sub-optimal  but  usable)
           IMAP  clients.   Besides,  there  are  also  some parts for IMAP servers present.  The most important
           lacking feature is support for encrypted connections.

       •   Mail::Box::Maildir

           Maildir folders have a directory for each folder.  A folder  directory  contains  "tmp",  "new",  and
           "cur"  sub-directories,  each containting messages with a different purpose.  Files with new messages
           are created in "tmp", then moved to "new" (ready to be accepted).  Later, they are moved to the "cur"
           directory (accepted).  Each message is one file with a name starting with timestamp.  The  name  also
           contains flags about the status of the message.

           Maildir folders can not be used on Windows by reason of file-name limitations on that platform.

       •   Mail::Box::Mbox

           A  folder  type  in  which all related messages are stored in one file.  This is a very common folder
           type for UNIX.

       •   Mail::Box::MH

           This folder creates a directory for each folder, and a message is one  file  inside  that  directory.
           The  message  files  are  numbered  sequentially on order of arrival.  A special ".mh_sequences" file
           maintains flags about the messages.

       •   Mail::Box::POP3 (read/delete only)

           POP3 is a protocol which can be used to retrieve messages from a remote system.  After the connection
           to a POP server is made, the messages can be looked at and removed  as  if  they  are  on  the  local
           system.

       •   Mail::Box::Netzwert

           The  Netzwert folder type is optimized for mailbox handling on a cluster of systems with a shared NFS
           storage.  The code is not released under GPL (yet)

       Other folder types are on the (long) wishlist to get implemented.   Please,  help  implementing  more  of
       them.

   Folder class implementation
       The   class   structure   of   folders   is   very   close   to   that  of  messages.   For  instance,  a
       Mail::Box::File::Message relates to a Mail::Box::File folder.  The folder types are:

                           Mail::Box::Netzwert
        Mail::Box::Mbox   | Mail::Box::Maildir Mail::Box::POP3
        |  Mail::Box::Dbx | | Mail::Box::MH    |  Mail::Box::IMAP4
        |  |               | | |                 |  |
        |  |               | | |                 |  |
        Mail::Box::File   Mail::Box::Dir       Mail::Box::Net
              |                  |                   |
              `--------------.   |   .---------------'
                             |   |   |
                             Mail::Box
                                 |
                                 |
                           Mail::Reporter (general base class)

       By far most folder features are implemented in Mail::Box, so available to all folder  types.   Sometimes,
       features  which  appear  in  only some of the folder types are simulated for folders that miss them, like
       sub-folder support for MBOX.

DIAGNOSTICS

       Warning: Changes not written to read-only folder $self.
           You have opened the folder read-only --which is the default set by new(access)--, made modifications,
           and now want to close it.  Set close(force) if you want to overrule the access  mode,  or  close  the
           folder with close(write) set to "NEVER".

       Error: Copying failed for one message.
           For  some  reason,  for  instance  disc  full, removed by external process, or read-protection, it is
           impossible to copy one of the messages.  Copying will proceed for the other messages.

       Error: Destination folder $name is not writable.
           The folder where the messages are copied to is not opened with write access (see new(access)).   This
           has no relation with write permission to the folder which is controled by your operating system.

       Warning: Different messages with id $msgid
           The  message  id  is discovered more than once within the same folder, but the content of the message
           seems to be different.  This should not be possible: each message must be unique.

       Error: Folder $name is opened read-only
           You can not write to this folder  unless  you  have  opened  the  folder  to  write  or  append  with
           new(access), or the "force" option is set true.

       Error: Folder $name not deleted: not writable.
           The  folder  must be opened with write access via new(access), otherwise removing it will be refused.
           So, you may have write-access according to the operating system, but that will not automatically mean
           that this "delete" method permits you to.  The reverse remark is valid as well.

       Error: Invalid timespan '$timespan' specified.
           The string does not follow the strict rules of the time span syntax which is permitted as parameter.

       Warning: Message-id '$msgid' does not contain a domain.
           According to the RFCs, message-ids need to contain a unique random part, then  an  "@",  and  then  a
           domain  name.   This  is  made  to  avoid the creation of two messages with the same id.  The warning
           emerges when the "@" is missing from the string.

       Error: No folder name specified.
           You did not specify the name of a folder to be opened.  Use the new(folder) option or set the  "MAIL"
           environment variable.

       Error: Package $package does not implement $method.
           Fatal  error:  the specific package (or one of its superclasses) does not implement this method where
           it should. This message means that some other related classes do implement this  method  however  the
           class  at  hand does not.  Probably you should investigate this and probably inform the author of the
           package.

       Error: Unable to create subfolder $name of $folder.
           The copy includes the subfolders, but for some reason it was not  possible  to  copy  one  of  these.
           Copying will proceed for all other sub-folders.

       Error: Writing folder $name failed
           For  some  reason (you probably got more error messages about this problem) it is impossible to write
           the folder, although you should because there were changes made.

SEE ALSO

       This module is part of  Mail-Box  distribution  version  2.110,  built  on  January  05,  2014.  Website:
       http://perl.overmeer.net/mailbox/

LICENSE

       Copyrights 2001-2014 by [Mark Overmeer]. For other contributors see ChangeLog.

       This  program  is  free  software;  you can redistribute it and/or modify it under the same terms as Perl
       itself.  See http://www.perl.com/perl/misc/Artistic.html

perl v5.18.1                                       2014-01-05                                     Mail::Box(3pm)