Hi all, Apologies for the duplicate post (a colleague of mine attempted to send it but I think it's been held for moderation as he's a new user).
Wondering if anybody on the list is from Microsoft or can assist in raising somebody at Microsoft to help with a strange delivery issue we are facing sending email to Outlook users. We are a web hosting company that has 10s of thousands of domains, spread across a few hundred servers emailing out through an outgoing email cluster. The cluster has multiple nodes and IPs. The servers sitting behind the outgoing email cluster (the 800 servers or so) all have hostnames ending in either domain1.com or domain2.com (not the actual domains). When a customer sends emails however, they use their own domain (user.com), so the only reference to the server is in the email header, however SPF/DKIM etc are all based on the customers domain (user.com ). We noticed after many complaints that all emails being sent from servers ending in domain2.com are getting scored by Outlook as SCL:9, regardless of email content, and has been for over a week now. We believe it's the server hostname that is appearing in the headers, as we migrated a customer's account (user.com) from a domain2.com server to a domain1.com server and then sent the EXACT same email and it gets a SCL:1 score - it's also worth noting that it used the identical outgoing email MTA and the same sending IP from the mail that was being scored SCL:9. We have reproduced this many times across multiple examples and can confirm that all domains and emails being sent from a domain2.com server are getting SCL:9, but the same email sent from the same sender email address (but using filtering nodes that have the domain1.com domain) are not getting flagged and getting scored SCL:1. We are quite positive that these nodes are not sending spam, and have done extensive investigations, SNDS is also showing no issues with our IPs. Further, since the MTA connecting to Outlook is the same for both groups of servers, we are relatively sure that it is not based on those IPs - but something to do with the server hostname itself. We have tried repeatedly to get in contact with Microsoft, but they come back with ..... less than useful responses. This has happened to us in the past many years ago, and the only fix was for Microsoft to remove the punishment on the domain that was there for some reason. If anybody can assist that would be greatly appreciated. Cheers, Angelo Giuffrida +61 421 221 585 Director, Nexigen Digital
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