Overview

Sendmail 8.13.3 is the latest version of Web upgrade available on the HP-UX 11i v1 and HP-UX 11i v2 operating systems at http://www.software.hp.com.

The main difference between Sendmail 8.11.1 and Sendmail 8.13.3 is that Sendmail 8.13.3 can act as a Mail Submission Program (MSP) using a different configuration file compared to the one used by the Sendmail daemon MTA. The /etc/mail/submit.cf file is the default Sendmail MSP configuration file.

When Sendmail starts up in the daemon mode, it listens both on the normal port 25 for incoming SMTP connections and on port 587 for the local submission of mail. The latter role is that of an MSA (documented in RFC 2476) and requires that Mail User Agents (MUAs) be explicitly coded to use port 587 for local submission of mail directly to the Sendmail daemon.

	NOTE: The role of the Sendmail daemon as an MSA (introduced on 8.11.1) is a different concept from that of the role of Sendmail as an MSP.

When Sendmail 8.13.3 is executed independently or invoked from a MUA to process locally submitted mail, Sendmail takes on the role of an MSP. MSP accepts and processes the submitted mail messages as a non-root user and queues them separately. After processing, MSP delivers the submitted mail messages to the Sendmail MTA daemon using the SMTP protocol through the port 25. The default /etc/mail/submit.cf file assumes that the MTA sendmail daemon is running on the local host.

When the Sendmail MTA is started, by default an additional Sendmail MSP queue-processing daemon is also started. The MSP queue daemon does not listen on any socket. The only purpose of the MSP queue daemon is to periodically scan the MSP mail queues for any mail messages accepted by MSP which have not yet been forwarded to the Sendmail MTA daemon.