I had updated the server to 7.2 on Monday December 28, 2009 around 4pm and the next day it had the issue listed above. I noted it, but didn’t look into it further because a restart of the services cured it for the time being. It came back today at 11:01am, so I created a support case for the issue. I received a callback from D. R. from SonicWall and he had me pull the Technical Support Package report from the Download section.
I attached it to the case and he checked it out. Said it was not related to the install of 7.2 but was caused by too many connections to the server.  My notes from the conversation with him are listed below:
TSP showed excess of 500 connections causing email flow to cease at 11:01am – 3:20pm(when services were restarted).
To address the issue we changed DHA protection from “delete” to “Reject invalid” with Tarpit=0. Also turned on Grid Network IP Reputation
Note: I restarted services after making those changes
