We have a customer who cannot email to a specific user in our network. Other outside accounts and internal users can email him fine.
Our internal user has an active directory account by his first initial and last name @OUR DOMAIN.com. A long time ago he got a lot of spam, so his email address was changed to just his last name@OUR DOMAIN.com, but his username stayed the same. that is the only thing I know that is different than other users on our network.
This is the message returned to the customer when emailing this internal user:
> This is the email server for the (OUR DOMAIN) domain.
> I'm sorry to have to inform you that the message returned
> below could not be delivered to one or more destinations.
> <(EMAIL WAS HERE)>: Permanent Failure: No account by that name here
How can I troubleshoot or solve this issue?