Provided by: procmail_3.22-26_amd64 
NAME
formail - mail (re)formatter
SYNOPSIS
formail [+skip] [-total] [-bczfrktedqBY] [-p prefix]
[-D maxlen idcache]
[-l folder]
[-x headerfield] [-X headerfield]
[-a headerfield] [-A headerfield]
[-i headerfield] [-I headerfield]
[-u headerfield] [-U headerfield]
[-R oldfield newfield]
[-n [maxprocs ]] [-m minfields] [-s [command [arg ...]]]
formail -v
DESCRIPTION
formail is a filter that can be used to force mail into mailbox format, perform `From ' escaping,
generate auto-replying headers, do simple header munging/extracting or split up a mailbox/digest/articles
file. The mail/mailbox/article contents will be expected on stdin.
If formail is supposed to determine the sender of the mail, but is unable to find any, it will substitute
`foo@bar'.
If formail is started without any command line options, it will force any mail coming from stdin into
mailbox format and will escape all bogus `From ' lines with a `>'.
OPTIONS
-v Formail will print its version number and exit.
-b Don't escape any bogus mailbox headers (i.e., lines starting with `From ').
-p prefix
Define a different quotation prefix. If unspecified it defaults to `>'.
-Y Assume traditional Berkeley mailbox format, ignoring any Content-Length: fields.
-c Concatenate continued fields in the header. Might be convenient when postprocessing mail with
standard (line oriented) text utilities.
-z Ensure a whitespace exists between field name and content. Zap fields which contain only a single
whitespace character. Zap leading and trailing whitespace on fields extracted with -x.
-f Force formail to simply pass along any non-mailbox format (i.e., don't generate a `From ' line as
the first line).
-r Generate an auto-reply header. This will normally throw away all the existing fields (except X-
Loop:) in the original message, fields you wish to preserve need to be named using the -i option.
If you use this option in conjunction with -k, you can prevent the body from being `escaped' by also
specifying -b.
-k When generating the auto-reply header or when extracting fields, keep the body as well.
-t Trust the sender to have used a valid return address in his header. This causes formail to select
the header sender instead of the envelope sender for the reply. This option should be used when
generating auto-reply headers from news articles or when the sender of the message is expecting a
reply.
-s The input will be split up into separate mail messages, and piped into a program one by one (a new
program is started for every part). -s has to be the last option specified, the first argument
following it is expected to be the name of a program, any other arguments will be passed along to
it. If you omit the program, then formail will simply concatenate the split mails on stdout again.
See FILENO.
-n [maxprocs]
Tell formail not to wait for every program to finish before starting the next (causes splits to be
processed in parallel). Maxprocs optionally specifies an upper limit on the number of concurrently
running processes.
-e Do not require empty lines to be preceding the header of a new message (i.e., the messages could
start on every line).
-d Tell formail that the messages it is supposed to split need not be in strict mailbox format (i.e.,
allows you to split digests/articles or non-standard mailbox formats). This disables recognition of
the Content-Length: field.
-l folder
Generate a log summary in the same style as procmail. This includes the entire "From " line, the
Subject: header field, the folder, and the size of the message in bytes. The mailstat command can
be used to summarize logs in this format.
-B Makes formail assume that it is splitting up a BABYL rmail file.
-m minfields
Allows you to specify the number of consecutive headerfields formail needs to find before it decides
it found the start of a new message, it defaults to 2.
-q Tells formail to (still detect but) be quiet about write errors, duplicate messages and mismatched
Content-Length: fields. This option is on by default, to make it display the messages use -q-.
-D maxlen idcache
Formail will detect if the Message-ID of the current message has already been seen using an idcache
file of approximately maxlen size. If not splitting, it will return success if a duplicate has been
found. If splitting, it will not output duplicate messages. If used in conjunction with -r,
formail will look at the mail address of the envelope sender instead at the Message-ID.
-x headerfield
Extract the contents of this headerfield from the header. Line continuations will be left intact;
if you want the value on a single line then you'll also need the -c option.
-X headerfield
Same as -x, but also preserves/includes the field name.
-a headerfield
Append a custom headerfield onto the header; but only if a similar field does not exist yet. If you
specify either one of the field names Message-ID: or Resent-Message-ID: with no field contents, then
formail will generate a unique message-ID for you.
-A headerfield
Append a custom headerfield onto the header in any case.
-i headerfield
Same as -A, except that any existing similar fields are renamed by prepending an ``Old-'' prefix.
If headerfield consists only of a field-name, it will not be appended.
-I headerfield
Same as -i, except that any existing similar fields are simply removed. If headerfield consists
only of a field-name, it effectively deletes the field.
-u headerfield
Make the first occurrence of this field unique, and thus delete all subsequent occurrences of it.
-U headerfield
Make the last occurrence of this field unique, and thus delete all preceding occurrences of it.
-R oldfield newfield
Renames all occurrences of the fieldname oldfield into newfield.
+skip
Skip the first skip messages while splitting.
-total
Output at most total messages while splitting.
NOTES
When renaming, removing, or extracting fields, partial fieldnames may be used to specify all fields that
start with the specified value.
By default, when generating an auto-reply header procmail selects the envelope sender from the input
message. This is correct for vacation messages and other automatic replies regarding the routing or
delivery of the original message. If the sender is expecting a reply or the reply is being generated in
response to the contents of the original message then the -t option should be used.
RFC822, the original standard governing the format of Internet mail messages, did not specify whether
Resent header fields (those that begin with `Resent-', such as `Resent-From:') should be considered when
generating a reply. Since then, the recommended usage of the Resent headers has evolved to consider them
as purely informational and not for use when generating a reply. This has been codified in RFC2822, the
new Internet Message Format standard, which states in part:
Resent fields are used to identify a message as having been reintroduced into the transport system
by a user. The purpose of using resent fields is to have the message appear to the final
recipient as if it were sent directly by the original sender, with all of the original fields
remaining the same....They MUST NOT be used in the normal processing of replies or other such
automatic actions on messages.
While formail now ignores Resent headers when generating header replies, versions of formail prior to
3.14 gave such headers a high precedence. If the old behavior is needed for established applications it
can be specified by calling formail with the option `-a Resent-' in addition to the -r and -t options.
This usage is deprecated and should not be used in new applications.
ENVIRONMENT
FILENO
While splitting, formail assigns the message number currently being output to this variable. By
presetting FILENO, you can change the initial message number being used and the width of the zero-
padded output. If FILENO is unset it will default to 000. If FILENO is non-empty and does not
contain a number, FILENO generation is disabled.
EXAMPLES
To split up a digest one usually uses:
formail +1 -ds >>the_mailbox_of_your_choice
or
formail +1 -ds procmail
To remove all Received: fields from the header:
formail -I Received:
To remove all fields except From: and Subject: from the header:
formail -k -X From: -X Subject:
To supersede the Reply-To: field in a header you could use:
formail -i "Reply-To: foo@bar"
To convert a non-standard mailbox file into a standard mailbox file you can use:
formail -ds <old_mailbox >>new_mailbox
Or, if you have a very tolerant mailer:
formail -a Date: -ds <old_mailbox >>new_mailbox
To extract the header from a message:
formail -X ""
or
sed -e '/^$/ q'
To extract the body from a message:
formail -I ""
or
sed -e '1,/^$/ d'
SEE ALSO
mail(1), sendmail(8), procmail(1), sed(1), sh(1), RFC822, RFC2822, RFC1123
DIAGNOSTICS
Can't fork Too many processes on this machine.
Content-Length: field exceeds actual length by nnn bytes
The Content-Length: field in the header specified a length that was longer than
the actual body. This causes this message to absorb a number of subsequent
messages following it in the same mailbox.
Couldn't write to stdout
The program that formail was trying to pipe into didn't accept all the data
formail sent to it; this diagnostic can be suppressed by the -q option.
Duplicate key found: x The Message-ID or sender x in this message was found in the idcache; this
diagnostic can be suppressed by the -q option.
Failed to execute "x" Program not in path, or not executable.
File table full Too many open files on this machine.
Invalid field-name: "x"
The specified field-name "x" contains control characters, or cannot be a partial
field-name for this option.
WARNINGS
You can save yourself and others a lot of grief if you try to avoid using this autoreply feature on mails
coming through mailinglists. Depending on the format of the incoming mail (which in turn depends on both
the original sender's mail agent and the mailinglist setup) formail could decide to generate an autoreply
header that replies to the list.
In the tradition of UN*X utilities, formail will do exactly what you ask it to, even if it results in a
non-RFC822 compliant message. In particular, formail will let you generate header fields whose name ends
in a space instead of a colon. While this is correct for the leading `From ' line, that line is not a
header field so much as the message separator for the mbox mailbox format. Multiple occurrences of such
a line or any other colonless header field will be considered by many mail programs, including formail
itself, as the beginning of a new message. Others will consider the message to be corrupt. Because of
this, you should not use the -i option with the `From ' line as the resulting renamed line, `Old-From ',
will probably not do what you want it to. If you want to save the original `From ' line, rename it with
the -R option to a legal header field such as `X-From_:'.
BUGS
When formail has to generate a leading `From ' line it normally will contain the current date. If
formail is given the option `-a Date:', it will use the date from the `Date:' field in the header (if
present). However, since formail copies it verbatim, the format will differ from that expected by most
mail readers.
If formail is instructed to delete or rename the leading `From ' line, it will not automatically
regenerate it as usual. To force formail to regenerate it in this case, include -a 'From '.
If formail is not called as the first program in a pipe and it is told to split up the input in several
messages, then formail will not terminate until the program it receives the input from closes its output
or terminates itself.
If formail is instructed to generate an autoreply mail, it will never put more than one address in the
`To:' field.
MISCELLANEOUS
Formail is eight-bit clean.
When formail has to determine the sender's address, every RFC822 conforming mail address is allowed.
Formail will always strip down the address to its minimal form (deleting excessive comments and
whitespace).
The regular expression that is used to find `real' postmarks is:
"\n\nFrom [\t ]*[^\t\n ]+[\t ]+[^\n\t ]"
If a Content-Length: field is found in a header, formail will copy the number of specified bytes in the
body verbatim before resuming the regular scanning for message boundaries (except when splitting digests
or Berkeley mailbox format is assumed).
Any header lines immediately following the leading `From ' line that start with `>From ' are considered
to be a continuation of the `From ' line. If instructed to rename the `From ' line, formail will change
each leading `>' into a space, thereby transforming those lines into normal RFC822 continuations.
NOTES
Calling up formail with the -h or -? options will cause it to display a command-line help page.
SOURCE
This program is part of the procmail mail-processing-package (v3.23pre) available at
http://www.procmail.org/ or ftp.procmail.org in pub/procmail/.
MAILINGLIST
There exists a mailinglist for questions relating to any program in the procmail package:
<procmail-users@procmail.org>
for submitting questions/answers.
<procmail-users-request@procmail.org>
for subscription requests.
If you would like to stay informed about new versions and official patches send a subscription request to
procmail-announce-request@procmail.org
(this is a readonly list).
AUTHORS
Stephen R. van den Berg
<srb@cuci.nl>
Philip A. Guenther
<guenther@sendmail.com>