Blocking Outgoing E-mail Addresses

On our website, we have a user registration system. When someone registers, they receive an e-mail with their username and password.

In our GWIA Defer folder, we get a buildup (maybe 50 per day) of undeliverable e-mails that are trying to send to what looks like random e-mail addresses in Russia (username@domain.ru). I assume that some type of robot is scanning our website and registering users.

Is there some way in GroupWise to block any e-mail going out to a .ru e-mail?

thanks,

david