Here are some of the highlights:
Implement ESMTP ETRN command to flush the queue for a specific host. The command takes a host name; data for that host is immediately (and asynchronously) flushed. Because this shares the -qR implementation, other hosts may be attempted, but there should be no security implications. Implementation from John Beck of InReference, Inc.RFC 1985 describes the new ETRN command, which is a safer version of the old TURN command, to start sending messages to rarely connected hosts.
Add three new command line flags to pass in DSN parameters: -V envid (equivalent to ENVID=envid on the MAIL command), -R ret (equivalent to RET=ret on the MAIL command), and -Nnotify (equivalent to NOTIFY=notify on the RCPT command). Note that the -N flag applies to all recipients; there is no way to specify per-address notifications on the command line, nor is there an equivalent for the ORCPT= per-address parameter.How to get notified when an e-mail has been read/delivered? gives an introduction to DSN.
Add MaxDaemonChildren option; if this is set, sendmail will start rejecting connections if it has more than this many outstanding children accepting mail. Note that you may see more processes than this because of outgoing mail; this is for incoming connections only. Add ConnectionRateThrottle option. If set to a positive value, the number of incoming SMTP connections that will be permitted in a single second is limited to this number. Connections are not refused during this time, just deferred. The intent is to flatten out demand so that load average limiting can kick in. It is less radical than MaxDaemonChildren, which will stop accepting connections even if all the connections are idle (e.g., due to connection caching). New SingleThreadDelivery option (requires HostStatusDirectory to operate). Avoids letting two sendmails on the local machine open connections to the same remote host at the same time. This reduces load on the other machine, but can cause mail to be delayed (for example, if one sendmail is delivering a huge message, other sendmails won't be able to send even small messages). Also, it requires another file descriptor (for the lock file) per connection, so you may have to reduce ConnectionCacheSize to avoid running out of per-process file descriptors. Based on the persistent host status code contributed by Paul Vixie and Mark Lovell.
Allow new named (not numbered!) config file rules to do validity
checking on SMTP arguments: check_mail for MAIL commands and
check_rcpt for RCPT commands. These rulesets can do anything
they want; their result is ignored unless they resolve to the
$#error mailer, in which case the indicated message is printed
and the command is rejected. Similarly, the check_compat
ruleset is called before delivery with "from_addr $| to_addr"
(the $| is a meta-symbol used to separate the two addresses);
it can give a "this sender can't send to this recipient"
notification. Note that this patch allows $| to stand alone
in rulesets.
Define new macros ${client_name}, ${client_addr}, and ${client_port}
that have the name, IP address, and port number (respectively)
of the SMTP client (that is, the entity at the other end of
the connection. These can be used in (e.g.) check_rcpt to
verify that someone isn't trying to relay mail through your
host inappropriately. Be sure to use the deferred evaluation
form, for example $&{client_name}, to avoid having these bound
when sendmail reads the configuration file.
Add new config file rule check_relay to check the incoming connection
information. Like check_compat, it is passed the host name
and host address separated by $| and can reject connections
on that basis.
Using check_* in sendmail 8.8
gives an overview how to use these rulesets.
CONFIG: allow mailertables to resolve to ``error:code message'' (where "code" is an exit status) on domains (previously worked only on hosts). Patch from Cor Bosman of Xs4all Foundation. CONFIG: allow mailertable entries to resolve to local:user; this passes the original user@host in to procmail-style local mailers as the "detail" information to allow them to do additional clever processing. From Joe Pruett of Teleport Corporation. CONFIG: allow any context that takes "mailer:domain" to also take "mailer:user@domain" to force mailing to the given user; "local:user" can also be used to do local delivery. This applies on *_RELAY and in the mailertable entries. Based on a suggestion by Ribert Kiessling of Easynet.
CONFIG: add FEATURE(limited_masquerade). Without this feature, any domain listed in $=w is masqueraded. With it, only those domains listed in a MASQUERADE_DOMAIN macro are masqueraded. CONFIG: add FEATURE(masquerade_entire_domain). This causes masquerading specified by MASQUERADE_DOMAIN to apply to all hosts under those domains as well as the domain headers themselves. For example, if a configuration had MASQUERADE_DOMAIN(foo.com), then without this feature only foo.com would be masqueraded; with it, *.foo.com would be masqueraded as well. Based on an implementation by Richard (Pug) Bainter of U. Texas.
CONFIG: add FEATURE(genericstable) to do a more general rewriting of outgoing addresses. Defaults to ``hash -o /etc/genericstable''. Keys are user names; values are outgoing mail addresses. Yes, this does overlap with the user database, and figuring out just when to use which one may be tricky. Based on code contributed by Richard (Pug) Bainter of U. Texas with updates from Per Hedeland of Ericsson.
CONFIG: add FEATURE(virtusertable) to do generalized rewriting of incoming addresses. Defaults to ``hash -o /etc/virtusertable''. Keys are either fully qualified addresses or just the host part (with the @ sign). For example, a table containing: info@foo.com foo-info info@bar.com bar-info @baz.org jane@elsewhere.net would send all mail destined for info@foo.com to foo-info (which is presumably an alias), mail addressed to info@bar.com to bar-info, and anything addressed to anyone at baz.org will be sent to jane@elsewhere.net. The names foo.com, bar.com, and baz.org must all be in $=w. Based on discussions with a great many people.
CONFIG: LOCAL_RULESETS introduces any locally defined rulesets, such as the check_rcpt ruleset. Suggested by Gregory Shapiro of WPI.