Mailrouting problem

Hello,

one question concerning mailrouting (release 8.5.1):

A user sends a mail to another user in the same domino domain (but on another server). He types the internet-adress “firstname.lastname@company.com”. Unfortunately there is an adjacent domain of the same name as “lastname”.

The mail is routed to firstname@lastname (to the adjacent domain) and not as intended to “firstname lastname” in the own domain.

What causes this behaviour and how could we correct this?

Thanks,

Peter