Outgoing Mail Messages

I recently had a user complaining to me that messages sent from my smtp server were all going into gmail & yahoo's bulk mail folders. I looked into it, checked their messages, and submitted requests to gmail and yahoo to find out exactly why this was happening. They both told me that Domain Keys or DKIM would help my users messages from not falsely ending up in spam fodlers on their servers. What is your take on this, and how would I integrate this into my virtualmin setups?

Status: 
Closed (fixed)