Is there a way of still using the friends lists but without the challenge messages?

I am always accessing that function via the Surgemail admin interface(default web port 7026) and then Accounts, select your account and then SPAM, then Advanced. 

You will find the various level settings for the Friends system.

On a per user basis, login to SurgeWeb as the user. Options(upper right corner), Spam control, Advanced.

Lyle Giese
LCR Computer Services, Inc.