Out of office problem

Hi all,

I have the strange problem with Out Of Office. When someone from internet sent e-mail to the person with OOO enabled the OOO reply correctly

But when someone from our partners which also have Lotus Domino (version 6.5.x) sent an e-mail using Lotus Domino e-mail address form (name/domain) to the person with OOO enabled, the OOO attach our internet domain and person receive mail delivery failure report. Does anybody have idea what is the problem and proper solution for this issue.