I keep getting SMTP errors like: 334 VXNlcm5hbWU6 UGFzc3dvcmQ6 Authentication unsuccessful [BL1PR13CA0304.namprd13.prod.outlook.com 2026-01-22T20:59:23.476Z 08DE59C2EA6C3D25]

and: '550 (x.x) [x.x.x.x]:xxxx is currently not permitted to relay through this server. Perhaps you have not logged into the pop/imap server in the last 30 minutes or do not have SMTP Authentication turned on in your email client.'

See also:

https://news.ycombinator.com/item?id=46724962

https://news.ycombinator.com/item?id=46724544

https://www.reddit.com/r/msp/comments/1qk45c0/microsoft_serv...

https://www.reddit.com/r/sysadmin/comments/1qk3tg7/microsoft...

https://www.reddit.com/r/sysadmin/comments/1qk518l/email_ser...

IMAP seems to also be having some sort of problem... Thunderbird has been stuck at "Looking up outlook.office365.com..." for a while.

Are we just immune to these headlines now because we don’t expect anything different from Microslop? Just an assumption that they’ll have a catastrophic failure once a quarter or more.

If you take a look, you can see comparable bumps during events like these across a wide array of sites and services, indicating a shared point of failure. Given the extreme weather, it's a tossup as to whether this was a fiber cut or a config screwup - could be bad BGP or routing, or possibly even an intentional cutover in preparation for possible outages, swapping primary and backup.

Lots of possible root causes, and it's at a level that consumers probably won't get a clear answer right away.