I set up my email address in Windows 10 Windows Live Mail  to  IMAP when I got the 'migrated to new server' message and for a few days it worked. Yesterday I tried to send an email and got the error message below. This still occurs. Has anything changed to stop me using WLM with outlook.com

An unknown error has occurred.

Subject 'from me ol'
Server Error: 550
Server Response: 550 5.3.4 554-554 5.2.0 STOREDRV.Deliver; delivery result banner
Server: 'smtp-mail.outlook.com'
Windows Live Mail Error ID: 0x800CCC69
Protocol: SMTP
Port: 587
Secure(SSL): Yes