365 Alias account

New Contributor

Created an alias account in 365. It was working, now when we send emails to it, it is Undelivered.


It now indicates something like "xxx was not found at xxx.com"


I went to the user account in 365 admin, and checked tried to add the alias again, but it indicated the it already exist. 


Any reason why the mail is undelivered? 

2 Replies



Thanks for your suggestion.


I reached out to a friend and he fixed it for me


He went into AD, to the user SIP, SMTP etc. in the user proxyaddress attribute field