Deleting account - blocked emails for domain?

Deleting account - blocked emails for domain?

Hi, yesterday I sent 2 urgent questions on your support, however, I cannot see them in the "sent" folder anymore.
Can you delete my account permanently for me? I tried to delete, and move it to my webhosting provider, but I still get: Google tried to deliver your message, but it was rejected by the server for the recipient domain ducabike.cz bymx.zohomail.com.  when I try to send anything to that mailbox, or any other created mailbox on my domain.

The error that the other server returned was:
553 Relaying disallowed

if you are already solving this, sorry for the spam, but I really need this solved as soon as possible!
thanks