Sophos Advisory: Emails being rejected

Overview

Emails being rejected as server configuration errors after upgrading Sophos Email Appliance (SEA) to 4.5.3.4.

Product and Environment

Sophos Email Appliance 4.5.3.4

Issue timeline

• 14-FEB-2023 08:00 UTC: Sophos tentatively plans to release the firmware with the fix on 16-Feb-23.
• 14-FEB-2023 00:20 UTC: Development is working on releasing a fix for this issue
• 11-FEB-2023: Our SEA team is currently investigating the issue.
• 11-FEB-2023 11:20 UTC: Issue was discovered.

Impact

Emails stop working after upgrading SEA to 4.5.3.4.

Current status

Identify the issue

Please verify the below server configuration error logs in the SEA appliance maillog:

Feb 11 13:40:55 mx100 postfix/smtpd[16198]: NOQUEUE: reject: RCPT from [domain] [IP address]: 451 4.3.5 Server configuration error; from= to= proto=ESMTP helo=

Feb 11 13:40:55 mx100 postfix/smtpd[14179]: NOQUEUE: reject: RCPT from [domain] [IP address]: 451 4.3.5 Server configuration error; from= to= proto=ESMTP helo=

Possible workaround

Do any of the following and check the status:

• Go to Configuration > Policy > SMTP Authentication > Ports and check that only port 25 is turned off.
• Turn off SMTP authentication.

Note: If the issue is not fixed, contact Sophos Support .