VESTACP - Email Error "Unrouteable address" can not send email out

 I've got some feedback can not send email out on VESTACP from end user, but in the past the email server work without problem 

After do a quick test the problem has located:

You also you use cli to check this problem :

dhviet@vcp01:/home/dhviet# sudo exim -bt viet.dh@XXX.YYY.ZZZ

viet.dh@@XXX.YYY.ZZZ is undeliverable: Unrouteable address

Its not a bug, our website developer added email domain on VestaCP, but we use O365 for email service instead. When exim tries to send the email, it looks in the local machine, then we should got failed Unrouteable address when we tried to send email out. Delete email domain on VestaCP to solve problem, at least in my case.

You can verified by cli: sudo exim -bt viet.dh@XXX.YYY.ZZZ , the result look like picture bellow:

For more detail: sudo exim -bt -d-resolver viet.dh@XXX.YYY.ZZZ

BTW : so edit # email domain to 0 in your packet on VestaCP to avoid developer mistake & be careful when creating the email domain when the mail server isn't manage on that server.