Greetings,
We seem to be having a problem with some users who are attempting to send e-mails from within the organisation to an external domain. Not all users are affected, and not all outgoing e-mails have this issue.
Some e-mails get stuck in the submission queue. This is the error message in Last Error : "A storage transient failure has occurred during content conversion."
Days later, the internal user who send the message gets a #550 4.4.7 QUEUE.Expired; message expired ## NDR.
We did have some initial configuration issues, but these were fixed more than a week ago :
- The external FQDN during EHLO was set to the wrong address, now pointing to the correct one.
- SPF record was updated with new IP adress.
Here is some additional information on the issue :
- Not on any blacklists - checked using dnsbl.info
- Telnet to remote servers works from exchange server, connections are accepted and can send mail.
- Outbound SMTP test ran using Microsoft Remote Connectivity Analyser : Passed with both External (Static) and Smarthost IP.
- This seems to happen only with emails that have an attachment and that are transfered, but only for the affected users.
- If content from these e-mails is manually copied over to a new email, email is sent to destination without problem.
Configuration information :
- Exchange 2013 running on Windows 2012 Datacenter with all latest updates.
- Outgoing e-mail is sent via smarthost. Only one outbound transport rule is active.
- Using internal DNS server.
- There is only one mailbox database.
Thank you for taking the time to read this!