We recently upgraded to the latest version of ComponentPro (UltimateMail) to get support for TLS 1.2. We performed the upgrade and tested our software out against a local mail server, which worked fine. When we went to deploy those changes to our production environment, our logs immediately started reporting a very high volume of ImapExceptions on the Connect calls from ComponentPro.Net.Mail.Imap. The exception message for all of these was "Timeout exceeded." This did not happen on every connection, but it happened on a large percentage of them.
As some background, this software runs on a five minute interval and connects to perhaps several hundred mail servers and pulls down email messages. Each mail server connection is handled on its own thread with its own instance of the Imap class. There is retry logic implemented for Connect calls, and each attempt fails out in the same way, with a "Timeout exceeded" exception.
We did not experience this problem prior to upgrading, and this was the only changed that was deployed when we started seeing the errors. I'm not sure which version of ComponentPro we upgraded from, but I believe it was a version that's at least a few years old.
Needless to say, we had to roll back the changes immediately when we started seeing this, so we can no longer use this library until whatever this problem is gets resolved. It seems likely that this problem stems from something introduced with a recent version of the ComponentPro library, because again, we did not see these exceptions prior to the upgrade.
Any assistance you can provide would be greatly appreciated.
asked 6/8/2018 4:26:49 PM