The difference between telemarketing and spam, IMHO, is that telemarketers make my phone ring, and that is something that demands immediate attention. That bothers me a lot. Much more than spam that might happen to be in the inbox when I check for it at my leisure. (I don't have automated email retrieval). I guess I have been fortunate that I am not innundated with spam. As some of my ISP provided email accounts that I guarded meticulously, and only sent to friends, leaked to (or were guessed by) spammers, I switched to gmail, which seems to have wonderful spam protection and spam reporting ease. Click a button and it's gone. Telemarketers, OTOH, are difficult to get rid of.
Lena