Forum Discussion
Persistent Outlook.com 550 5.7.520 AS(4810) outbound blocking across multiple clients
I’m trying to resolve an intermittent outbound sending problem on a personal Hotmail/Outlook.com account. Messages are being rejected with: 550 5.7.520 – Message blocked because it contains content...
Honestly, reading the full account, I’d lean more towards an issue with the Outlook.com account's reputation or a false positive from Microsoft's outbound filters—perhaps someone reported your email as spam or abusive, and you ended up on an internal blacklist.
Unfortunately, only their support team can unblock it.