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Hi

We manage a number of on-premise Exchange Servers

We have one particular client who has a sender that cannot deliver email in to the business.
This has only started happening in the last 2 weeks. Prior to this they were able to send email with out issue and they are the only sender reporting a problem.

The client has a perimeter Sophos XG Firewall and I think this is where the issue is
We have a bounce message from the sender (Anonymised as best as I can) and is attached

Any feedback or support on the issue would be appreciated.

Thank you
Andy

Bouce Message from Sender.pdf (160.8 KB)

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5.4.317 Message expired, cannot connect to remote server

The destination server is down or misconfigured. It also mentions expired root, so the other side may need to renew their certificate.

FYI, you’ve not masked all of the details in that PDF.

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CN=Sophos_CA_C1B0A6GBV2BMD52 - this may be the root cause of the issue?

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After creating a new hybrid SSL certificate that you need to add the FQDN of that gateway, office 365 users were able to send to on-premises users without issues.

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On top of the great advice already given, this tool is handy. And I wouldn’t be surprised if all the MSPs on Spiceworks have DM’ed you about migrating to O365.

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I would first question on your expertise and proficiency on Exchange servers (not a pun) as you (or ur company) earn a living on managing exchange servers ?

Then as a managing agent, you should have access to MS support as well ?

As this is only 1 sender to 1 customer (with SXG), then the most common would be

  • XSG blocking for some reason (look at XSG logs )
  • sender sending from unknown or blocked domain or compromised outlook client (ask them cc to gmail and hotmail accounts)