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Sendmail 8.13.3 includes the following new features: Security enhancements Sendmail 8.13.3 can be run as a non-setuid program
for better security purposes. Any attempt from non-superusers to obtain
root user privileges is denied. Sendmail 8.13.3 supports secured mail transactions
using the Transport Layer Security (TLS) protocol.
Anti-Spam control Sendmail 8.13.3 supports libmilter.a, the mail filtering APIs.
LDAP enhancements to support recursion and LDAP URL
support Sendmail 8.13.3 supports the Lightweight Directory
Access Protocol (LDAP) recursion based on the attribute specifications
in an LDAP-map definition. LDAP recursion allows LDAP queries to return
a new query, a DN, or an LDAP URL, which is in turn queried. The default LDAP specifications for AliasFile (O AliasFile=ldap:) and file classes (F{X}@LDAP) are
extended to include support for LDAP recursion using new attributes.
The daemon process ID (PID) files are locked so that
other daemons cannot overwrite PID files of each other. Sendmail 8.13.3 includes the authinfo feature to allow a separate database for SMTP AUTH information. When Sendmail 8.13.3 receives a temporary error on
a RCPT TO: command, it attempts to
contact other MX hosts, if available. The recipient list used for delivery is ordered by hostsignature, the character string version of MX
records. This sorts recipients for the same MX records together so
that small portions of the list need to be scanned instead of the
whole list. The sorting is done for each delivery() pass, to determine piggybacking. The significance of the change
is better when the recipient list is large. hostsignature is now created during recipient list creation rather than during
delivery. The previous piggybacking called ‘coincidental’
is extended to a more opportunistic piggybacking called ‘coattail’.
Rather than complete MX record matching (coincidental), piggybacking
is done if just the lowest value preference matches (coattail). New Queueing features implemented in Sendmail 8.13.3 Following are the new queueing features: All queue runners can be terminated using a SIGTERM to the parent. A new option, QueueFileMode, is added for the default permissions of queue files. A new parallel queue runner code is added. It allows
multiple queue runners for each work group to process the same work.
A work group is a collection of one or more queues in a multi-queue
environment. The MaxQueueChildren option is added to limit the number of concurrent active queue runner
processes. The MaxRunnersPerQueue option specifies the maximum number of queue runners for each queue
group. A queue member selection by substring pattern matching
now allows the pattern to be negated. For the options -qI, -qR and -qS, you can specify -q!I, -q!R, and -q!S to remove members of the queue that match during processing. The -qp [time] option
is added to fork a single child for each queue that sleeps between
queue runs. This option is similar to -qtime option that is used to periodically fork a child to process the
queue. You can send a SIGHUP signal
to restart this persistent queue runner. The SIGHUP signal
now restarts a Sendmail process that runs the queue at an interval
of 15 minutes. The NiceQueueRun option
sets the priority of queue runners. The -qf and -v option run the Sendmail queue in the foreground.
Normally, Sendmail runs the queue in the background when Sendmail
is invoked with the -q option. Sendmail runs the queue in the background when Sendmail is invoked
with -q option. However, if you use
the new -qf option or -v option, Sendmail runs the queue in the foreground. The value QueueSortOrder=Random sorts the queue randomly. This feature is useful when several queue
runners are started manually to avoid contention. The value QueueSortOrder=Modification sorts the queue based on the time when the qf file was modified.
Support for DeliverBy SMTP extension (RFC 2852): Support for RFC 2852 (Deliver by SMTP Service
Extension), that allows a client to specify an amount of
time within which an email must be delivered. A new option DeliveryByMin is added to set the minimum amount
of time or to disable the extension.
MX records are looked up for the FallBackMXhost. To revert to the previous behavior where no MX record are referred,
enclose the host name in square brackets (‘[’ and ‘]’). The DelayLA option
delays connections if the load average exceeds the specified value.
The default value for DelayLA is
zero. A value greater than zero causes Sendmail 8.13.3 to sleep for
one second on most SMTP commands and before accepting connections,
if the load average is exceeded.
Sendmail 8.13.3 includes the following additional new options: LDAP map options: The -w option allows
you to specify the LDAP API or protocol version. The -H option allows
you to specify an LDAP URL instead of specifying the LDAP server using
a -h host and -p port. With the -H option, you can
use LDAP over SSL and connections through named sockets if your LDAP
library supports it the security feature.
The MailboxDatabase option specifies the type of mailbox database used to look up local
mail recipients; the default value for this option is pw, which indicates that getpwnam() is used. You can use the new mailbox database types to add custom
code to libsm or mbdb.c. If the new option FastSplit has a value greater than zero, it suppresses the MX lookups on addresses
when they are initially sorted. This may result in faster envelope
splitting. If the mail is submitted directly from the command line,
the value also limits the number of processes to deliver the envelopes;
if more envelopes are created they are only queued up and must be
processed by a queue run.
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