Could it also be their outlook for mobile connections, where the connection fails for some other reason, like the server don't like the features supported? It seems to use some sort of proxy, where outlook's server connects to the server in question instead of a direct connection from the phone to server.
-----Ursprungligt meddelande----- Från: Dan Malm via mailop <mailop@mailop.org> Skickat: den 14 augusti 2023 11:06 Till: mailop@mailop.org; ab...@microsoft.com Ämne: [mailop] Abuse AUTH from Microsoft outlook IP space Hi, Since Friday I'm seeing a rather extreme amount of SMTP AUTH requeusts from the same IPv6 IP space that outlook.com uses when sending emails on behalf of customers that have added an "external" address to sync and send from to their outlook account. The AUTH uses valid credentials for the accounts but just hangs up after AUTH. The amount of connections seems to increase daily. For the last 24h I have ~11M AUTH requests but only ~5K mails actually sent from the 2603:1026::/32 range. I also see some similar patterns from the other ranges that seems to send outlook mail: 2603:1036::/32, 2603:1046::/32, 2603:1056::/32 but the bulk of it is from the 1026 one. Anyone from MS listening that would like to comment? -- BR/Mvh. Dan Malm, Systems Engineer, one.com _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
