A screenshot of the mailing list that says: It finally happened! The mailop list server has been blocked by Microsoft, resulting in a slew of suspended subscriptions. The problem I have is that I simply can't reach the link they provide in the error message: *Diagnostic-Code*: smtp; 550 5.7.1 Unfortunately, messages from [91.132.147.157] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BC88DCCD3A3675] [BN3PEPF0000B06E.namprd21.prod.outlook.com 2025-12-29T08:43:13.886Z 08DE446E687E5366] The link redirects 3 or 4 times to a page which gives a 500 internal server error. This happens regardless of browser, OS, whether logged in to an MS account or using private/incognito mode. In the absence of any other capability to address this with MS by following their directions, subscribers using live/outlook/Hotmail addresses should consider their subscriptions at risk.