Usermin : How to deal with legitimate spam

Some of my users emails from the same domain are being identified as spam. In usermin how can I tell it that there emails are OK and to stop blocking them.

For example :

When sends an email to it gets reported as spam and not delivered to the inbox.

I guess I could make a global adjustment to spamassasin but then I will have everyone else calling me saying that they are getting to much spam.

Any help/guidance appreciated.