HP-UX Mailing Services Administrator's Guide

Sendmail 8.13.3
New Features in Sendmail 8.13.3
Chapter 3 123
Performance Features
Sendmail 8.13.3 contains the following performance enhancement
features:
• “The FastSplit Option” on page 123
• “SMTP Pipelining” on page 124
• “Connection Caching” on page 124
The following sections discuss the Sendmail 8.13.3 performance features
in detail.
The FastSplit Option
You can use the FastSplit option to suppress MX lookups before
splitting an envelope and to limit the number of envelopes that can be
delivered on the initial attempt. The FastSplit option syntax is as
follows:
-OFastSplit=num
where, num is of type numeric.
If num is a negative nonnumeric value, or zero, Sendmail enforces initial
sorting based on MX records.
If num is set to a value greater than zero, the initial MX lookups on
addresses are suppressed when they are sorted which may result in
faster envelope splitting. If the mail is submitted directly from the
command line, then the value also limits the number of processes to
deliver the envelopes.
When Sendmail expands an alias, as when using aliases to send to a
mailing list, Sendmail sorts the list of new recipients by host. Normally,
the list of hosts is then sorted by MX records rather than host name.
After sorting, the new MX-sorted list is split by Sendmail into multiple
envelopes.
Envelope splitting creates multiple envelopes when there is originally
only one. Each new envelope contains fewer envelope recipients.
Normally, all these envelopes are delivered in parallel for delivery
efficiency.