formail - mail (re)formatter

       Stephen R. van den Berg
              <srb@cuci.nl>

                                                     BuGless                                          FORMAIL(1)

       When formail has to generate a leading `From ' line it normally will contain the current date.   If  for‐
       mail  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 regener‐
       ate 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.

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 `>'.

       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  mes‐
                              sages 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 for‐
                              mail 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 diagnos‐
                              tic 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.

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.

       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'

       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).

       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 white‐
       space).

       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.

       formail - mail (re)formatter

       Calling up formail with the -h or -? options will cause it to display a command-line help page.

-v   Formail will print its version number and exit.

       -b   Don't escape any bogus mailbox headers (i.e., lines starting with `From ').

       -pprefix
            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  headersender  instead  of the envelopesender 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.

       -lfolder
            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.

       -mminfields
            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-.

       -Dmaxlenidcache
            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 mailaddress of the envelope sender instead at the Message-ID.

       -xheaderfield
            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.

       -Xheaderfield
            Same as -x, but also preserves/includes the field name.

       -aheaderfield
            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.

       -Aheaderfield
            Append a custom headerfield onto the header in any case.

       -iheaderfield
            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.

       -Iheaderfield
            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.

       -uheaderfield
            Make the first occurrence of this field unique, and thus delete all subsequent occurrences of it.

       -Uheaderfield
            Make the last occurrence of this field unique, and thus delete all preceding occurrences of it.

       -Roldfieldnewfield
            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.

mail(1), sendmail(8), procmail(1), sed(1), sh(1), RFC822, RFC2822, RFC1123

       This program is part of  the  procmailmail-processing-package  (v3.24)  available  at  http://www.proc‐
       mail.org/ or ftp.procmail.org in pub/procmail/.

formail [+skip] [-total] [-bczfrktedqBY] [-pprefix]
            [-Dmaxlenidcache]
            [-lfolder]
            [-xheaderfield] [-Xheaderfield]
            [-aheaderfield] [-Aheaderfield]
            [-iheaderfield] [-Iheaderfield]
            [-uheaderfield] [-Uheaderfield]
            [-Roldfieldnewfield]
            [-n [maxprocs ]] [-mminfields] [-s [command [arg ...]]]
       formail-v

       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_:'.