We have been experiencing email delay issues to Messagelabs.com recipient addresses for 2 months. Only Messagelabs, no other recipients. We have had our customers open tickets with Symantec to try and resolve the issue. We have supplied verbose SMTP logs to Symantec both via tickets and here on the Forums. Each time, Syamntec stops responding as soon as the evidence shows this isn't a quick fix and possibly a Symantec issue. We have log evidence that shows our email server (only 1 sending IP address that is clean with Symantec) will make a good TLS connection to a Messagelabs.com tower and 20 minutes later it fails to the same tower. Messagelabs will drop all new connections with a "ConnectionReset" timeout. Always 4 minutes after we send our SSL cert to them.
Symatnec states that they are not throttling our traffic, but all evidence looks like they are. On Mondays, our email traffic goes with little to no delay. By Tuesday, mid-morning, delays start to build from 2-4 hours. Overnight, our queses clear up. The next day, the delays build faster and last longer. By Friday, we still have email from Thursday in our outbound queue. Over the weekend, when we are not sending mail, the queues clear and we have no problems sending again on Monday AM.
Becasue we are not a Symantec customer ourselves, we can't directly open a ticket. We have had to rely on our customers to act as a middleman to Syamntec each time and then Symantec even stops responding to them. Could I PLEASE, get a response from a Symantec Engineer who can spend a little time to resolve the issue. We are not the first person to post about the same email delays. Even if it requires a configuration change on our end, many others will benefit from knowing what messagelabs is looking for to make routine good connections.
Hopefull for a response,
-Bob Scott, Network Admin, Laddawn MFG.