Changed MX & no longer getting root emails.

[partsace]

Changed primary_hostname & no longer getting root emails.

I have changed the primary_hostname in exim from mail.x.com to mailhost.x.com. I want to get the mail that needs to be delivered to root but my system says that [email protected] does not exist.

Where do I change mail.x.com to mailhost.x.com so I can get my root email?

  [email protected]
    No Such User Here

Thanks,

Scott