nosuch user

[rudy]

I have a problem , I have qpopper (newer version) running on linux 6.2
we are an isp , and one of our isdn customers cant send mail to anyone
at its own isp ( us )
it gives them an error saying there is no such user !!
they  can send mail everywhere except  to the people at its own isp !

any suggestions ?
comment?


Help ME!!

Rudy