If you think a DreamHost customer is behind illegal activities such as spamming, fraud, copyright infringement, etc… your first stop should be the Dreamhost Abuse Center. (Not the forums)

The Abuse Center’s purpose is to assist anyone experiencing abusive activities originating from or associated with Dreamhost servers, and also educate DreamHost customers on acceptable practices for bulk email, copyrights, trademarks, etc.

DreamHost offers specific instructions for:

If you’ve been spammed by a DreamHost customer Report spam/UBE to DreamHost.

If a DreamHost customer has infringed upon your copyright/trademark: Report copyright infringement or trademark infringement to DreamHost.  For other abuse situations please see the Abuse Center Homepage for more information.