Greetings. We are having some issues with email since last friday. Out of the blue, some emails are not reaching our users mailbox. Mostly emails from Gmail. Emails from Hotmail, for example, have no problem on getting in. When I send a email from a Gmail account, I receive this error on the gmail side: """ This is an automatically generated Delivery Status Notification THIS IS A WARNING MESSAGE ONLY. YOU DO NOT NEED TO RESEND YOUR MESSAGE. Delivery to the following recipient has been delayed: Technical details of temporary failure: Unspecified Error (SENT_SECOND_EHLO): Connection reset by peer """ We are running Exchange Server 2007 in one box. SMTP server is running on another box, running ISA 2006. The mx1 record point to the ISA server. This issue is driving me nuts, so any help would be very appreciated. Best regards

Hi Have you changed your TLS settings or is it possible that your certificate for SMTP has expired or is no longer valid for some other reason? Cheers, Steve

Thank you for your reply. Our certificate is valid until 2015, and is enabled to All Intended Purposes. When you say TLS settings, were should I check that? Thank you once again!

If you don't know where they are then I'm guessing that you haven't changed them :) It would be on the Authentication tab of your receive connector properties.

It is correct. I haven't changed this setting. TLS is turned on. Update: Some emails sent from Gmail, are arriving with more than 24h delay Some don't arrive at all.

What about the cert on your ISA server, more than likely it's a cert name mismatch. James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com

That NDR isn't from Exch, gmail are having issue with connectionsbeing reset, so it's an issue there or along the way up to your ISA. Check your ISA logs and see what connections are being accepted/rejected. May want post in the ISA forum for any specific details on ISA.Sukh

It was a certificate problem, on our SMTP that was installed on ISA server. ISA server has the right certificate. In the Default SMTP Virtual Server-Properties-Access-Certificate, I had once imported the certificate to that place also. I think the problems started to happen since that day. I removed the certificate from there, and It started receiving emails. Strange...Thank you all for the help!