Successful TLS connections registered but no email recieved

[Christian Juel-Jensen]

Hi, we have set up ESA for a new customer and they reported that no email from a particular domain came through. 

Looking at the message tracking logs gave no evidence that the sending domain attempted to send any mail but when we looked at the TLS connection logs we saw a lot of successful TLS establishments for that domain. 

Can anyone share some insight in to what is the probable cause of this and how to successfully debug this, while we await investigations from the sending party?

Best regards

Christian

[Libin Varghese]

Hi Christian,

We would probably want to check if the sending party gets a bounce back email that would point us in the right direction to start with.

TLS may fail verification if that is turned on under Mail Policies -> Mail Flow Policies, and the sending party does not have a valid certificate.

On the ESA you could try reviewing the mail_logs for any connections that were rejected or aborted.

grep "ip/hostname of the sending server" mail_logs

We could also set up a packet capture for the sending server IP and have them send a couple of test emails for review.

From the GUI Help & Support -> Packet Capture

Thanks!

Libin Varghese

[Christian Juel-Jensen]

Thanks for your efforts. However, here we discovered that there was hardcoded requirements set at the sending side that was the casue of the failiure. We had to contact the sender to update their configuration for our domain name.

[Libin Varghese]

Thank you for the update.

Glad it was resolved.

Libin V