550 relaying denied to

Hi all

I have received in some cases the following message:

550 relaying denied to user@domain.com

Whe have configured that send the messages leaving the local domain to a antivirus server.

Nothing else special in outbound is configured can somebody help me

Subject: 550 relaying denied to

Do any of these results help?

http://www-10.lotus.com/ldd/nd6forum.nsf/Search?SearchView&Query=550%20AND%20relaying&SearchOrder=0&Start=1&Count=100