Provided by: libmail-box-perl_3.012-1_all 
NAME
Mail::Box::File - handle file-based folders
INHERITANCE
Mail::Box::File
is a Mail::Box
is a Mail::Reporter
Mail::Box::File is extended by
Mail::Box::Mbox
SYNOPSIS
DESCRIPTION
"Mail::Box::File" is the base-class for all file-based folders: folders which bundle multiple messages
into one single file. Usually, these messages are separated by a special line which indicates the start
of the next one.
Extends "DESCRIPTION" in Mail::Box.
OVERLOADED
Extends "OVERLOADED" in Mail::Box.
overload: "" stringification
Inherited, see "OVERLOADED" in Mail::Box
overload: @{} use as ARRAY
Inherited, see "OVERLOADED" in Mail::Box
overload: cmp string comparison
Inherited, see "OVERLOADED" in Mail::Box
METHODS
Extends "METHODS" in Mail::Box.
Constructors
Extends "Constructors" in Mail::Box.
$class->new(%options)
Inherited, see "Constructors" in Mail::Box
-Option --Defined in --Default
access Mail::Box 'r'
body_delayed_type Mail::Box Mail::Message::Body::Delayed
body_type <see description>
coerce_options Mail::Box +[]
create Mail::Box false
extract Mail::Box 10240
field_type Mail::Box undef
fix_headers Mail::Box false
folder Mail::Box $ENV{MAIL}
folderdir Mail::Box $ENV{HOME}.'/Mail'
head_delayed_type Mail::Box Mail::Message::Head::Delayed
head_type Mail::Box Mail::Message::Head::Complete
keep_dups Mail::Box false
lock_extension '.lock'
lock_file Mail::Box <foldername><lock-extension>
lock_timeout Mail::Box 1 hour
lock_type Mail::Box Mail::Box::Locker::DotLock
lock_wait Mail::Box 10 seconds
locker Mail::Box undef
log Mail::Reporter 'WARNINGS'
manager Mail::Box undef
message_type Mail::Box Mail::Box::File::Message
multipart_type Mail::Box Mail::Message::Body::Multipart
remove_when_empty Mail::Box true
save_on_exit Mail::Box true
trace Mail::Reporter 'WARNINGS'
trusted Mail::Box <depends on folder location>
write_policy undef
access => $mode
body_delayed_type => CLASS
body_type => CLASS|CODE
The default "body_type" option for "File" folders, which will cause messages larger than 10kB to be
stored in files and smaller files in memory, is implemented like this:
sub determine_body_type($$)
{ my $head = shift;
my $size = shift || 0;
'Mail::Message::Body::' . ($size > 10000 ? 'File' : 'Lines');
}
coerce_options => ARRAY
create => BOOLEAN
extract => INTEGER | CODE | METHOD | 'LAZY'| 'ALWAYS'
field_type => CLASS
fix_headers => BOOLEAN
folder => FOLDERNAME
folderdir => $directory
head_delayed_type => CLASS
head_type => CLASS
keep_dups => BOOLEAN
lock_extension => $file|STRING
When the dotlock locking mechanism is used, the lock is created with a hardlink to the folder file.
For "Mail::Box::File" type of folders, this filename is by default named as the folder-file itself
followed by ".lock". For example: the "Mail/inbox" folder file will have a hardlink made as
"Mail/inbox.lock".
You may specify an absolute $file, a relative (to the folder's directory) filename, or an extension
(preceded by a dot). So valid examples are:
.lock # appended to the folder's filename
my_own_lockfile.test # full filename, same dir
/etc/passwd # somewhere else
When the program runs with less privileges (as normal user), often the default inbox folder can not
be locked with the lockfile name which is produced by default.
lock_file => $file
lock_timeout => $seconds
lock_type => CLASS|STRING|ARRAY
lock_wait => $seconds
locker => OBJECT
log => LEVEL
manager => $manager
message_type => CLASS
multipart_type => CLASS
remove_when_empty => BOOLEAN
save_on_exit => BOOLEAN
trace => LEVEL
trusted => BOOLEAN
write_policy => 'REPLACE'|'INPLACE'|undef
Sets the default write policy, as default for a later call to write(policy). With "undef", the
best policy is autodetected.
Attributes
Extends "Attributes" in Mail::Box.
$obj->filename()
Returns the filename for this folder, which may be an absolute or relative path to the file.
» example:
print $folder->filename;
$obj->fixHeaders()
Inherited, see "Attributes" in Mail::Box
$obj->folderdir( [$directory] )
Inherited, see "Attributes" in Mail::Box
$obj->isTrusted()
Inherited, see "Attributes" in Mail::Box
$obj->logSettings()
Inherited, see "Attributes" in Mail::Reporter
$obj->name()
Inherited, see "Attributes" in Mail::Box
$obj->removeEmpty()
Inherited, see "Attributes" in Mail::Box
$obj->type()
Inherited, see "Attributes" in Mail::Box
The folder
Extends "The folder" in Mail::Box.
$obj->addMessage($message, %options)
Inherited, see "The folder" in Mail::Box
$obj->addMessages(@messages)
Inherited, see "The folder" in Mail::Box
$class->appendMessages(%options)
Appending messages to a file based folder which is not opened is a little risky. In practice, this
is often done without locking the folder. So, another application may write to the folder at the
same time... :( Hopefully, all goes fast enough that the chance on collision is small.
All %options of Mail::Box::Mbox::new() can be supplied. Improves base, see "The folder" in Mail::Box
-Option --Defined in --Default
folder Mail::Box <required>
lock_type NONE
message Mail::Box undef
messages Mail::Box undef
share Mail::Box <C<false>>
folder => FOLDERNAME
lock_type => ...
See Mail::Box::new(lock_type) for possible values.
message => MESSAGE
messages => ARRAY-OF-MESSAGES
share => BOOLEAN
$obj->close(%options)
Inherited, see "The folder" in Mail::Box
$obj->copyTo($folder, %options)
Inherited, see "The folder" in Mail::Box
$obj->delete(%options)
Inherited, see "The folder" in Mail::Box
$obj->organization()
Inherited, see "The folder" in Mail::Box
$obj->size()
Inherited, see "The folder" in Mail::Box
$obj->update(%options)
Inherited, see "The folder" in Mail::Box
$obj->url()
Inherited, see "The folder" in Mail::Box
Folder flags
Extends "Folder flags" in Mail::Box.
$obj->access()
Inherited, see "Folder flags" in Mail::Box
$obj->isModified()
Inherited, see "Folder flags" in Mail::Box
$obj->modified( [BOOLEAN] )
Inherited, see "Folder flags" in Mail::Box
$obj->writable()
Inherited, see "Folder flags" in Mail::Box
The messages
Extends "The messages" in Mail::Box.
$obj->current( [$number|$message|$message_id] )
Inherited, see "The messages" in Mail::Box
$obj->find($message_id)
Inherited, see "The messages" in Mail::Box
$obj->findFirstLabeled( $label, [BOOLEAN, [$msgs]] )
Inherited, see "The messages" in Mail::Box
$obj->message( $index, [$message] )
Inherited, see "The messages" in Mail::Box
$obj->messageId( $message_id, [$message] )
Inherited, see "The messages" in Mail::Box
$obj->messageIds()
Inherited, see "The messages" in Mail::Box
$obj->messages( <'ALL'|$range|'ACTIVE'|'DELETED'|$label| !$label|$filter> )
Inherited, see "The messages" in Mail::Box
$obj->nrMessages(%options)
Inherited, see "The messages" in Mail::Box
$obj->scanForMessages($message, $message_ids, $timespan, $window)
Inherited, see "The messages" in Mail::Box
Sub-folders
Extends "Sub-folders" in Mail::Box.
$any->listSubFolders(%options)
Inherited, see "Sub-folders" in Mail::Box
$any->nameOfSubFolder( $subname, [$parentname] )
Inherited, see "Sub-folders" in Mail::Box
$obj->openRelatedFolder(%options)
Inherited, see "Sub-folders" in Mail::Box
$obj->openSubFolder($subname, %options)
Inherited, see "Sub-folders" in Mail::Box
$any->topFolderWithMessages()
Inherited, see "Sub-folders" in Mail::Box
Internals
Extends "Internals" in Mail::Box.
$obj->coerce($message, %options)
Inherited, see "Internals" in Mail::Box
$any->create($foldername, %options)
Inherited, see "Internals" in Mail::Box
-Option --Defined in--Default
folderdir Mail::Box undef
folderdir => $directory
$obj->determineBodyType($message, $head)
Inherited, see "Internals" in Mail::Box
$any->folderToFilename( $foldername, $folderdir, [$subext] )
Translate a $foldername into a filename, using the $folderdir value to replace a leading "=". The
optional $subext is only used for MBOX folders.
$class->foundIn( [$foldername], %options )
Inherited, see "Internals" in Mail::Box
$obj->lineSeparator( [<STRING|'CR'|'LF'|'CRLF'>] )
Inherited, see "Internals" in Mail::Box
$obj->locker()
Inherited, see "Internals" in Mail::Box
$obj->messageCreateOptions( [$type, $config] )
Returns a key-value list of options to be used each time a new message is read from a file. The list
is preceded by the $type of message which has to be created.
This data is used by readMessages() and updateMessages(). With $type and $config, a new
configuration is set.
$obj->moveAwaySubFolder($directory, $extension)
The $directory is renamed by appending the $extension, which defaults to ".d", to make place for a
folder file on that specific location. "false" is returned if this failed.
$obj->parser()
Create a parser for this mailbox. The parser stays alive as long as the folder is open.
$obj->read(%options)
Inherited, see "Internals" in Mail::Box
$obj->readMessages(%options)
Inherited, see "Internals" in Mail::Box
$obj->storeMessage($message)
Inherited, see "Internals" in Mail::Box
$obj->toBeThreaded($messages)
Inherited, see "Internals" in Mail::Box
$obj->toBeUnthreaded($messages)
Inherited, see "Internals" in Mail::Box
$obj->updateMessages(%options)
For file based folders, the file handle stays open until the folder is closed. Update is therefore
rather simple: move to the end of the last known message, and continue reading... Improves base, see
"Internals" in Mail::Box
$obj->write(%options)
Inherited, see "Internals" in Mail::Box
-Option --Defined in --Default
force Mail::Box false
policy undef
save_deleted Mail::Box false
force => BOOLEAN
policy => 'REPLACE'|'INPLACE'|undef
In what way will the mail folder be updated. If not specified during the write, the value of the
new(write_policy) at folder creation is taken.
Valid values:
• "REPLACE"
First a new folder is written in the same directory as the folder which has to be updated, and
then a call to move will throw away the old immediately replacing it by the new.
Writing in "REPLACE" module is slightly optimized: messages which are not modified are copied
from file to file, byte by byte. This is much faster than printing the data which is will be
done for modified messages.
• "INPLACE"
The original folder file will be opened read/write. All message which where not changed will
be left untouched, until the first deleted or modified message is detected. All further
messages are printed again.
• "undef"
As default, or when "undef" is explicitly specified, first "REPLACE" mode is tried. Only when
that fails, an "INPLACE" update is performed.
"INPLACE" will be much faster than "REPLACE" when applied on large folders, however requires the
"truncate" function to be implemented on your operating system (at least available for recent
versions of Linux, Solaris, Tru64, HPUX). It is also dangerous: when the program is interrupted
during the update process, the folder is corrupted. Data may be lost.
However, in some cases it is not possible to write the folder with "REPLACE". For instance, the
usual incoming mail folder on UNIX is stored in a directory where a user can not write. Of course,
the "root" and "mail" users can, but if you want to use this Perl module with permission of a
normal user, you can only get it to work in "INPLACE" mode. Be warned that in this case folder
locking via a lockfile is not possible as well.
save_deleted => BOOLEAN
$obj->writeMessages(%options)
Inherited, see "Internals" in Mail::Box
Other methods
Extends "Other methods" in Mail::Box.
$any->timespan2seconds($time)
Inherited, see "Other methods" in Mail::Box
Error handling
Extends "Error handling" in Mail::Box.
$obj->AUTOLOAD()
Inherited, see "Error handling" in Mail::Reporter
$obj->addReport($object)
Inherited, see "Error handling" in Mail::Reporter
$any->defaultTrace( [$level]|[$loglevel, $tracelevel]|[$level, $callback] )
Inherited, see "Error handling" in Mail::Reporter
$obj->errors()
Inherited, see "Error handling" in Mail::Reporter
$any->log( [$level, [$strings]] )
Inherited, see "Error handling" in Mail::Reporter
$any->logPriority($level)
Inherited, see "Error handling" in Mail::Reporter
$obj->notImplemented()
Inherited, see "Error handling" in Mail::Reporter
$obj->report( [$level] )
Inherited, see "Error handling" in Mail::Reporter
$obj->reportAll( [$level] )
Inherited, see "Error handling" in Mail::Reporter
$obj->trace( [$level] )
Inherited, see "Error handling" in Mail::Reporter
$obj->warnings()
Inherited, see "Error handling" in Mail::Reporter
Cleanup
Extends "Cleanup" in Mail::Box.
$obj->DESTROY()
Inherited, see "Cleanup" in Mail::Box
DETAILS
File based folders
File based folders maintain a folder (a set of messages) in one single file. The advantage is that your
folder has only one single name, which speeds-up access to all messages at once.
The disadvantage over directory based folder (see Mail::Box::Dir) is that you have to construct some
means to keep all message apart, for instance by adding a message separator, and this will cause
problems. 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.
DETAILS
Extends "DETAILS" in Mail::Box.
DIAGNOSTICS
Error: Cannot append messages to folder file $filename: $!
Appending messages to a not-opened file-organized folder may fail when the operating system does not
allow write access to the file at hand. Cast by appendMessages()
Error: Cannot create directory $dir for folder $name.
While creating a file-organized folder, at most one level of directories is created above it.
Apparently, more levels of directories are needed, or the operating system does not allow you to
create the directory. Cast by create()
Error: Cannot create folder file $name: $!
The file-organized folder file cannot be created for the indicated reason. In common cases, the
operating system does not grant you write access to the directory where the folder file should be
stored. Cast by create()
Error: Cannot get a lock on $type folder $self.
A lock is required to get access to the folder. If no locking is needed, specify the NONE lock type.
Cast by new()
Error: Cannot move away sub-folder $dir
Cast by moveAwaySubFolder()
Warning: Cannot remove folder $name file $filename: $!
Writing an empty folder will usually cause that folder to be removed, which fails for the indicated
reason. new(remove_when_empty) Cast by write()
Warning: Cannot remove folder $name file $filename: $!
Writing an empty folder will usually cause that folder to be removed, which fails for the indicated
reason. new(remove_when_empty) controls whether the empty folder will removed; setting it to "false"
(0) may be needed to avoid this message. Cast by write()
Error: Cannot replace $filename by $tempname, to update folder $name: $!
The replace policy wrote a new folder file to update the existing, but was unable to give the final
touch: replacing the old version of the folder file for the indicated reason. Cast by write()
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". Cast by close()
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. Cast by
copyTo()
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 controlled by your operating system.
Cast by copyTo()
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. Cast by
messageId()
Info: File $filename for folder $self does not exist.
Cast by new()
Error: File too short to get write message $nr ($size, $need)
Mail::Box is lazy: it tries to leave messages in the folders until they are used, which saves time
and memory usage. When this message appears, something is terribly wrong: some lazy message are
needed for updating the folder, but they cannot be retrieved from the original file anymore. In this
case, messages can be lost.
This message does appear regularly on Windows systems when using the 'replace' write policy. Please
help to find the cause, probably something to do with Windows incorrectly handling multiple
filehandles open in the same file. Cast by write()
Warning: Folder $name file $file is write-protected.
The folder is opened writable or for appending via new(access), but the operating system does not
permit writing to the $file. The folder will be opened read-only. Cast by new()
Error: Folder $name not deleted: not writable.
The folder must be opened with write access via new(access), otherwise removing it will be refused.
So, you may have write-access according to the operating system, but that will not automatically mean
that this "delete" method permits you to. The reverse remark is valid as well. Cast by delete()
Error: Invalid timespan '$timespan' specified.
The string does not follow the strict rules of the time span syntax which is permitted as parameter.
Cast by timespan2seconds()
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. Cast by messageId()
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. Cast by notImplemented()
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. Cast by copyTo()
Error: Unable to update folder $self.
When a folder is to be written, both replace and inplace write policies are tried, If both fail, the
whole update fails. You may see other, related, error messages to indicate the real problem. Cast
by write()
SEE ALSO
This module is part of Mail-Box version 3.012, built on November 27, 2025. Website:
http://perl.overmeer.net/CPAN/
LICENSE
For contributors see file ChangeLog.
This software is copyright (c) 2001-2025 by Mark Overmeer.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
programming language system itself.
perl v5.40.1 2025-12-07 Mail::Box::File(3pm)