Is there a market for selling safelists credits? I have over 4 million credits on several safelists like adtactics, adtroopers, global, trafficpro, etc. If used according to each safelist rules, it would mean sending out around half a million emails per month. It's almost impossible not to obtain some results from this.
Not sure about the DP rules for selling these credits but you could check out the DP Marketplace and see if they allow this or ask one of the moderators.