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NAME
formail - mail (re)formatter
SYNOPSIS
formail [+skip] [-total] [-vbczfrktedqBY] [-p prefix]
[-D maxlen idcache]
[-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
...]]]
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 con-
tent. Zap fields which contain only a single whi-
tespace character. Zap leading and trailing whitespace
on fields extracted with -x.
-f Force formail to simply pass along any non-mailbox for-
mat (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 extract-
ing 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 splitted 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 for-
mats). This disables recognition of the Content-
Length: field.
-B Makes formail assume that it is splitting up a BABYL
rmail file.
-m minfields
Allows you to specify the number of consecutive header-
fields 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, display it as a single line.
-X headerfield
Same as -x, but also preserves 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 header-
field 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 mes-
sage then the -t option should be used.
RFC822, the original standard governing the format of Inter-
net 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 normally generating a reply. 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 for-
mail 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 genera-
tion 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 mail-
box 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), binmail(1), sendmail(8), procmail(1), sed(1),
sh(1), RFC822, 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 follow-
ing 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 diag-
nostic 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 execut-
able.
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 incom-
ing 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.
BUGS
When formail has to generate a leading `From ' line it nor-
mally 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 expect-
ed 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, in-
clude -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 al-
ways 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).
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
(v3.15) 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@gac.edu>