NAME

setforward - create a forwarding database

SYNOPSIS

setforward cdb tmp

DESCRIPTION

setforward reads a table of forwarding instructions from its standard input. It converts the table into a forwarding database. The forwarding database can be used by fastforward.

setforward writes the forwarding database to tmp; it then moves tmp to cdb. tmp and cdb must be on the same filesystem.

If there is a problem creating tmp, setforward complains and leaves cdb alone.

The forwarding database format is portable across machines.

INSTRUCTION FORMAT

A forwarding instruction contains a target, a colon, a series of commands, and a semicolon. Each command is a recipient address, owner address, external mailing list, or program. Commands are separated by commas.

For example,

   root@yp.to: god@heaven.af.mil, staff@af.mil;

says that mail for root@yp.to should be forwarded to the recipient addresses god@heaven.af.mil and staff@af.mil.

When setforward sees # it ignores all text from # to the end of the line:

   # this is a comment

setforward ignores all other line endings, so you can split a forwarding instruction across lines. It also ignores spaces and tabs. Exception: you can put a space (or tab or comma or whatever) into a target or command by putting a backslash in front of it. (However, NUL bytes are not permitted anywhere.)

TARGETS

When fastforward sees the incoming address user@host.dom, it tries three targets: user@host.dom, @host.dom, and user@. It obeys the commands for the first target that it finds. Target names are interpreted without regard to case.

All the commands for a single target must be listed in a single instruction. Exception: an owner address can be listed in a separate instruction.

RECIPIENT ADDRESSES

If a command begins with an ampersand, setforward takes the remaining bytes in the command as a recipient address:

   boss@yp.to: &god@heaven.af.mil;

fastforward sends each incoming mail message to the recipient address. The recipient address must include a fully qualified domain name. It cannot be longer than 800 bytes.

If a recipient address is itself a target in the forwarding table, fastforward will recursively handle the instructions for that target. Note that @host.dom and user@ wildcards do not apply here; they apply only to the incoming address.

If a command begins with a letter or number, setforward takes the entire command as a recipient address:

   boss@yp.to: god@heaven.af.mil;

OWNER ADDRESSES

If a command begins with a question mark, setforward takes the remaining bytes in the command as an owner address:

   sos@heaven.af.mil: ?owner-sos@heaven.af.mil;

fastforward uses that address as the envelope sender for forwarded mail, so bounces will go back to that address. (Normally, if a message is forwarded to a bad address, it will bounce back to the original envelope sender.)

EXTERNAL MAILING LISTS

If a command begins with a dot or slash, setforward takes the entire command as the name of a binary mailing list file created by setmaillist:

   sos@heaven.af.mil: /etc/lists/sos.bin;

fastforward will read and obey the commands in that file. The file must be world-readable and accessible to fastforward.

PROGRAMS

If a command begins with a vertical bar or exclamation point, setforward takes the rest of the command as the name of a program to run:

   dew@: |dew-monitor;

For a vertical bar, fastforward feeds the message to that program. An exclamation point works the same way except that fastforward inserts $UFLINE, $RPLINE, and $DTLINE in front of the message.

DUPLICATES

When fastforward is building the recipient list for a message, it keeps track of the recipient addresses and external mailing lists it has used. If the same command shows up again, it skips it. For example:

   everybody@yp.to: programmers@yp.to, testers@yp.to;
   programmers@yp.to: joe@yp.to, bob@yp.to;
   testers@yp.to: joe@yp.to, fred@yp.to;

A message to everybody@yp.to will be sent to joe@yp.to only once. (This also means that addresses in an internal forwarding loop are discarded.)

Exception: If a target has an owner address, commands for that target are considered different from commands for ``outside'' targets.