Clam Antivirus -- corrupt virus scanner DBs were found on two mailservers that affected receipt of incoming mail. Content has been replaced with the latest signature files. Suspect a recent update may have pulled in incompatible definitions causing the corruption.
A few services failed to launch after a rebooted of the main mail server this morning. Major players involved were
smtp - cause of all the client connection failures to the imap server
saslauthd - intermediate program which handles authentication on behalf of the imap server.
mailing lists and mail delivery were unaffected by the outage. Only client connections and interactive access were affected.
All known problems have been resolved. Let us know of any lingering issues.
-- JoeyArmstrong 28 Feb, 2011