Date: 2026/January 22 - 2:30 PM ET US / 19:30 GMT
Starting around Jan 22 17:47 GMT (about 2.75 hours ago), Office365 overall started returning the following SMTP response immediately when connecting to it: 451 4.3.2 Temporary server error. Please try again later ATTR2
This is happening whether it is coming from SpamTitan or otherwise
--- this is from outside / direct connect to office365
$ telnet hidden-com.mail.protection.outlook.com 25
Connected to hidden-com.mail.protection.outlook.com.
Escape character is '^]'.
220 BN2PEPF00004FBF.mail.protection.outlook.com Microsoft ESMTP MAIL Service ready at Thu, 22 Jan 2026 19:34:04 +0000 [08DE5971186BD36A]
EHLLO
500 5.3.3 Unrecognized command 'Length: 5' [BN2PEPF00004FBF.namprd04.prod.outlook.com 2026-01-22T19:34:09.871Z 08DE5971186BD36A]
EHLO ghghgh.com
250-BN2PEPF00004FBF.mail.protection.outlook.com Hello [54.77.158.79]
250-SIZE 157286400
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-STARTTLS
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 SMTPUTF8
MAIL FROM: <fenu@titanhq.com>
451 4.3.2 Temporary server error. Please try again later ATTR2 [BN2PEPF00004FBF.namprd04.prod.outlook.com 2026-01-22T19:34:28.958Z 08DE5971186BD36A]
SpamTitan will periodically retry Deferred message that Office365 can't accept right now because of the "451 4.3.2 Temporary server error."
==> this seems to be across Office365 regions.
Update: 3:30 PM ET / 20:30 GMT
Office365 DownDectector shows the same:
Microsoft 365 down? Current problems and outages | Downdetector
Update: 4:10 PM ET / 21:10 GMT
Office365 is still saying:
451 4.3.2 Temporary server error. Please try again later ATTR2
Update: 6:00 PM ET / 23:00 GMT
Office365 is still saying:
451 4.3.2 Temporary server error. Please try again later ATTR2 [DS3PEPF0000C37E.namprd04.prod.outlook.com 2026-01-22T22:59:02.274Z 08DE595FA1033005] (in reply to MAIL FROM command)
Update: 9:15 PM ET / 02:15 GMT
We are continuing to monitor, but the number of Deferred messages going to Office365 has gotten significantly less in the last 1.5 hours.
Update: 10:15 PM ET / 3:15 GMT
The Office365 Server errors seemed to have stopped completely, and the Deferred Queues are back to normal.