Mailers

There are fewer mailers supported in this version than the previous version, owing mostly to a simpler world. As a general rule, put the MAILER definitions last in your .mc file, and always put MAILER(smtp) before MAILER(uucp) -- several features and definitions will modify the definition of mailers, and the smtp mailer modifies the UUCP mailer.

local	The local and prog mailers. You will almost always need these; the only exception is if you relay ALL your mail to another site. This mailer is included automatically.
smtp	The Simple Mail Transport Protocol mailer. This does not hide hosts behind a gateway or another other such hack; it assumes a world where everyone is running the name server. This file actually defines four mailers: `"smtp"` for regular (old-style) SMTP to other servers, `"esmtp"` for extended SMTP to other servers, `"smtp8"` to do SMTP to other servers without converting 8-bit data to MIME (essentially, this is your statement that you know the other end is 8-bit clean even if it doesn't say so), and `"relay"` for transmission to our `SMART_HOST`, `LUSER_RELAY`, or `MAIL_HUB`.
uucp	The Unix-to-Unix Copy Program mailer. Actually, this defines two mailers, `"uucp-old"` (a.k.a. "uucp") and `"uucp-new"` (a.k.a. "suucp"). The latter is for when you know that the UUCP mailer at the other end can handle multiple recipients in one transfer. If the smtp mailer is also included in your configuration, two other mailers (`"uucp-dom"` and `"uucp-uudom"`) are also defined [warning: you MUST specify `MAILER(smtp)` before `MAILER(uucp)`]. When you include the uucp mailer, sendmail looks for all names in the `$=U` class and sends them to the `uucp-old` mailer; all names in the `$=Y` class are sent to `uucp-new`; and all names in the `$=Z` class are sent to `uucp-uudom`. Note that this is a function of what version of rmail runs on the receiving end, and hence may be out of your control. See the section describing UUCP mailers in more detail.
usenet	Usenet (network news) delivery. If this is specified, an extra rule is added to ruleset 0 that forwards all local email for users named ``group.usenet'' to the ``inews'' program. Note that this works for all groups, and may be considered a security problem.
fax	Facsimile transmission. This is experimental and based on Sam Leffler's HylaFAX software.
pop	Post Office Protocol.
procmail	An interface to procmail (does not come with sendmail). This is designed to be used in mailertables. For example, a common question is "how do I forward all mail for a given domain to a single person?". If you have this mailer defined, you could set up a mailertable reading: host.com procmail:/etc/procmailrcs/host.com with the file /etc/procmailrcs/host.com reading: :0 # forward mail for host.com ! -oi -f $1 person@other.host This would arrange for (anything)@host.com to be sent to person@other.host. Within the procmail script, `$1` is the name of the sender and `$2` is the name of the recipient. If you use this with `FEATURE(local_procmail)`, the FEATURE should be listed first.
mail11	The DECnet mail11 mailer, useful only if you have the mail11 program from gatekeeper.dec.com:/pub/DEC/gwtools (and DECnet, of course). This is for Phase IV DECnet support; if you have Phase V at your site you may have additional problems.
phquery	The phquery program. This is somewhat counterintuitively referenced as the `"ph"` mailer internally. It can be used to do CCSO name server lookups. The `phquery` program, which this mailer uses, is distributed with the ph client.
cyrus	The `cyrus` and `cyrusbb` mailers. The cyrus mailer delivers to a local cyrus user. This mailer can make use of the `"user+detail@local.host"` syntax; it will deliver the mail to the user's "detail" mailbox if the mailbox's ACL permits. The cyrusbb mailer delivers to a system-wide cyrus mailbox if the mailbox's ACL permits.

The local mailer accepts addresses of the form "user+detail", where the "+detail" is not used for mailbox matching but is available to certain local mail programs (in particular, see FEATURE(local_procmail)). For example, "eric", "eric+sendmail", and "eric+sww" all indicate the same user, but additional arguments <null>, "sendmail", and "sww" may be provided for use in sorting mail.