Using Outlook for iOS for personal email and calendar management
Hello. It’s possible you have a rule set up that’s trying to forward your emails to another address that’s either full or doesn’t exist, causing you to receive a postmaster undeliverable message.
To check, open Outlook web or the New Outlook app, click on Settings ⚙️, then go to Mail > Rules.
Check for any rules you don’t recognize, and if you find one, delete it right away. This could mean someone else created it, which might indicate your account’s been compromised. If that’s the case, remove the rule, change your password, and turn on 2FA to help keep your account safe.