aliasing/forwarding loop broken

[Kiriray]

Hello,

What does this error message mean?

----- The following addresses had permanent fatal errors -----
<joeblow@domain.com> :include:dom_joeblow.txt
(expanded from: <joeblow@domain.com>)

----- Transcript of session follows -----
550 :include:dom_joeblow.txt... Cannot open dom_joeblow.txt: No such file
or directory 554 <joeblow@domain.com>... aliasing/forwarding loop broken

this was generated when a user tried to send a message to joeblow@domain.com. His email setup in outlook express is correct, we're using Sendmail for NT to administer their email accounts and nothing has been changed on the server.
The user can send email no problem.

help.

thanks