Today at about 10:00 AM, the HelpDesk reported major failure in WebMail.
We noticed the presence of a large number of processes (about 1000 and growing) on the mail server, and a larger than normal of mail in-queue. WebMail was stopped, server processes on the mail server were stopped, and the mail queues were processed by hand.
When the queues had been processed, the imap, pop, and sendmail processes were started up, as was WebMail.
At this point the number of processes grew steadily up to about 1300. Then problems with both IMAP (WebMail and desktop client-based) and POP connections began showing themselves as timeouts.