The MTA (mail server) process restarts following a failure to initialize an antivirus update.

bmclient log:
2013-03-07T12:02:04-05:00 (ERROR:26691.3086038736): [20125] ECOM engine failed to initialize using rules /data/scanner/rules/bm_ruleset.2.avsym.1362675679 with result code 10.
2013-03-07T12:02:06-05:00 (ERROR:26691.3086038736): [20125] ECOM engine failed to initialize using rules /data/scanner/rules/bm_ruleset.2.avsym.1362668650 with result code 10.
2013-03-07T12:02:06-05:00 (ALERT:26691.3086038736): [24032] After error loading Symantec AntiVirus engine from /data/scanner/rules/bm_ruleset.2.avsym.1362675679, another error occurred while reloading Symantec AntiVirus engine from /data/scanner/rules/bm_ruleset.2.avsym.1362668650 - so the server crashed.

maillog:
2013 Mar  7 12:02:11 EST (err) runner[31224]: Job mta process 26691 exited, terminated on signal 11 (0x008B).
 

This is a rare but known issue which has been addressed in SMG version 10.0.3.

Workaround method for version 10.0.2 or earlier:

Restart MTA (mail server) process to address the issue via the Control Center Administration->Configuration->hostname->Services page. Alternately, the MTA may be restarted from the command line interface via the `service mta restart` command.