MAILDELIVERY(5)

NAME
maildelivery

SYNOPSIS
User delivery specification file

DESCRIPTION
The delivery of mail by the local channel can run through various courses, including using a user tailorable file. The delivery follows the following strategy, giving up at any point it considers the message delivered.

    1)  If the address indicates a pipe or file default then that is carried out.

    2)  The file .maildelivery (or something similar) in the home directory is read if it exists and the actions in it are followed.

    3)  A system-wide file is consulted next, such as /usr/lib/maildelivery and the actions are similar to 2.

    4)  If the message still hasn't been delivered, then it is put into the user's normal mailbox (.mail or mailbox) depending on the system.

The format of the .maildelivery file is
    field <FS> pattern <FS> action <FS> result <FS> string
where
is name of a field that is to be searched for a pattern. This is any header field that you might find in a message. The most commonly used headers are usually From, to, cc, subject and sender. As well as the standard headers, there are some psuedo-headers that are can also be used. These are :-
    The out of band sender information. This is the address MMDF would use for reporting delivery problems with the message. the address that was used to mail to you, normally 'yourname' or 'yourname=string' (see below). if the message hasn't been delivered yet, this field is matched. this case is always true regardless of any other action.
is some sequence of characters that may be matched in the above field. Case is not significant.

action
    is one of the mail delivery actions supported by the local channel. Currently the supported actions are file or >, which appends the message to the given file, with delimiters; pipe or |, which starts up a process with the message as the standard input; and destroy which throws the message away. There is also qpipe or ^, which fakes a pipe command and is quicker than the standard pipe, but does not do header reformatting.
    For piped commands, the exit status of the command is significant. An exit status of 0 implies that the command succeeded and everything went well. An exit status of octal 0300-0377 indicates that a permanent failure occured and the message should be rejected; these error codes are given in mmdf.h. Any other exit status indicates a temporary failure and the delivery attempt will be aborted and restarted at a later time. is one of the letters A, R or ? which stand for Accept, Reject and "Accept if not delivered yet". They have the following effects:
    If the result of this line's action is OK, then the message can be considered delivered. The message is not to be considered delivered by this action. This is equivalent to A except that the action is not carried out if the message has already been accepted.

The file is always read completely so that several matches can be made, and several actions taken. As a security check, the .maildelivery file must be owned by either the user or root, and must not have group or general write permission. In addition the system delivery file has the above restrictions but must also be owned by root. If the field specified does not need a pattern a dash (-) or similar symbol is usually inserted to show that the field is present but not used. The field separator character can be either a tab, space or comma (,). These characters can be included in a string by quoting them with double quotes (") (double quotes can be included with a backslash '\').

MMDF treats local addresses which contain an equals sign ('=') in a special manner. Everything in a local address from an equals sign to the '@' is ignored and passed on to the local channel. The local channel will make the entire string available for matching against the addr string of the .maildelivery file. For example, if you were to subscribe to a digest as "foo=digest@bar.NET", submit and the local channel will verify that it is legal to deliver to "foo", but then the entire string "foo=digest" will be available for string matching against the .maildelivery file for the addr field.

ENVIRONMENT
The environment in which piped programs are run contains a few standard features, specifically:

HOME is set to the user's home directory.
USER is set to the user's login name.
SHELL is set to the user's login shell (defaults to /bin/sh).

The default umask is set up to 077, this gives a very protective creation mask. Initgroups is called if the 4.2 version of UNIX is running. If further requirements are needed, then a shell script can be run first to set up more complex environments.

There are certain built-in variables that you can give to a piped program. These are $(sender), $(address), $(size), $(reply-to) and $(info). $(sender) is set to the return address for the message. $(address) is set to the address that was used to mail to you, normally `yourname' or `yourname=string'. $(size) is set to the size in bytes of this message. $(reply-to) is set to the Reply-To: field (or the From: field if the former is missing) and so can be used for automatic replies. $(info) is the info field from the internal mail header and is probably only of interest to the system maintainers.

EXAMPLE

Here is a rough idea of what a .maildelivery file looks like:

# lines starting with a '#' are ignored.
# as are blank lines
# file mail with mmdf2 in the "To:" line into file mmdf2.log
To~~~~mmdf2~~~~file~~~~A~~~~mmdf2.log
# Messages from mmdf pipe to the program err-message-archive
From~~~~mmdf~~~~pipe~~~~A~~~~err-message-archive
# Anything with the "Sender:" address "uk-mmdf-workers"
# file in mmdf2.log if not filed already
Sender~~~~uk-mmdf-workers~~~~file~~~~?~~~~mmdf2.log
# "To:" unix - put in file unix-news
To~~~~Unix~~~~>~~~~A~~~~unix-news
# if the address is jpo=mmdf - pipe into mmdf-redist
Addr~~~~jpo=mmdf~~~~|~~~~A~~~~mmdf-redist
# if the address is jpo=ack - send an acknowledgement copy back
Addr~~~~jpo=ack~~~~|~~~~R~~~~"resend~~-r~~$(reply-to)"
# anything from steve - destroy!
from~~~~steve~~~~destroy~~~~A~~~~-
# anything not matched yet - put into mailbox
default~~~~-~~~~>~~~~?~~~~mailbox
# always run rcvalert
*~~~~-~~~~|~~~~R~~~~rcvalert

FILES
$HOME/.maildelivery - the file's normal location.
/usr/lib/maildelivery - the system file. This should be protected against attack. It may contain contents such as:

default~~~~-~~~~pipe~~~~A~~~~stdreceive
*~~~~-~~~~|~~~~R~~~~ttynotify

This allows interfacing to non-standard mail systems, ones that don't believe in delimiter-separated mailboxes.

SEE ALSO
rcvtrip(1)

BUGS
And why not?