Unrouteable address!!! Any way to fix ??

[wimp]

I upgrade to latest Edge version (as suggested from CPsupport)and reinstalled exim
but nothing to do... default addresse give still errors
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This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

userid@domain.com
Unrouteable address
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Cpanel support please advice on how to fix that problem..
Thanks

[wimp]

ok just realized that the problem is for only 1 domain...


so what could be the problem there...