I hear this problem happening a lot. the scum of the internet using domains from businesses to send out spam. I get about 15 emails a day from postmaster@somedomain.com saying emails sent from random addresses like mspkvjui@mattsoft.net couldn't be delivered. they're advertising stock investment opportunities for other companies. I have sent out emails to 2 of the companies using that spammer, saying to cease and desist or I will be forced to sue, but haven't heard a thing from them. is there anything I can do to stop this before my domain is put on a spam blacklist for anti-spam programs?