Customers may receive NDRs when sending Outbound emails using *.comcastbusiness.net. These emails will not show in the Central Email logs at the moment.
Applies to the following Sophos product(s) and version(s) Central Email, Email Appliance, PMX
Customers using/going through *.comcastbusiness.net to deliver emails may receive an NDR message back indicating something similar:
554 5.7.1 Service unavailable; Unverified Client host [<address>-static.hfc.comcastbusiness.net] blocked using sophosxl.com
There has also been some reports of this affecting other domains and inbound emails as well.
As of around December 27th, 23:20 UTC the issue to and from comcastbusiness IPs is now resolved. If there are any reports of problems for domains with no relation to comcast, please contact Sophos Technical Support and reference this article.
This article will be updated as additional information is collected.
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