365 Alias account

[Kirt2021]

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]

Hi, do a message trace to get more details.

https://docs.microsoft.com/en-us/exchange/monitoring/trace-an-email-message/message-trace-modern-eac

[#3]

@ChristianBergstrom 

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