In some configurations, the Messaging Gateway (SMG) mail server process (MTA) may exit with a signal 6 and restart. If alerts are configured this will generate one or more admin alert messages.
Subject: mta crashed on signal 6 on [mail host name]
mta crashed on signal 6 on [mail host name]
exit code: 0x0086
This issue has been addressed with the Messaging Gateway 10.6.2 release.
Please see the Messaging Gateway Administration Guide for detailed instructions on how to update the SMG software.
Disable DKIM validation via "Spam > Sender Authentication > DKIM > Enable DomainKeys Identified Mail (DKIM) validation for all incoming mail" and monitor the affected system. This may stop or reduce the frequency with which the process restarts.