In my experience as another low-volume sender who has run into S3140s (I have posted here about it, not sure why your mailop search didn't find it). Submitting the form, following up, doing anything at all over 10 weeks got me no response or change. I ended up routing emails to MS addresses via another host. Then a couple of months later it unblocked, so I have this week reverted but put in place a log monitor to check for if it happens again. YMMV, but I wouldn't put any value in the form or the process behind it. Simon
On Tuesday, July 21, 2026 18:07 AEST, Sean Kamath via mailop <[email protected]> wrote: Hello all, I’m a super low volume sender (basically, family only) and today I emailed someone at hotmail and got: > <redacted>@hotmail.com: 550 5.7.1 Unfortunately, messages from [45.32.136.82] > weren't sent. Please contact your Internet service provider since part of > their network is on our block list (S3140). You can also refer your provider > to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol > Filter Agent][AGT=PFA][MxId=11BDC63846E9567C] > [AMS0EPF000001B7.eurprd05.prod.outlook.com 2026-07-21T07:15:41.759Z > 08DEE31C291DD028] Searching my mailop archives for S3140 only finds one hit (from Michael Wise in 2022). From Michael Wise’s signature, and also the link on https://substrate.office.com/ip-domain-management-snds/Postmaster/Troubleshooting (followed from the link in the above rejection message) the form to use is http://go.microsoft.com/fwlink/?LinkID=614866 I see other messages that shows the form to use is at https://olcsupport.office.com/, but I think that is for S3150 (perhaps a different product group?). Either one requires me to log in with a Microsoft account. Is there a form I can use that doesn’t require a login, or should I just make one so I can fill out the form? Thanks, Sean _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
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