I once has a newsletter sign-up on one of my websites through GetResponse. I went in to actually look at the list and discovered there were only a couple of entries that might have been real people. The rest - several hundred - were obvious spammers and phishers with addresses like bankofamerica at yahoo dot com or paypal at hotmail dot com or "friend" at something dot whatever in China or Rumania or . . .
I deleted the list, took the form off my site, cancelled GetResponse, and have not looked back.
The money may be in someone's list but it sure as heck wasn't in that one.
Another time I purchased some leads (not cheap stale ones) and loaded them into another autoresponder. I would always put myself on any list to see what the message looked like - if it even came through. Much of the time my own copy (literally from me to me) did not make it to my personal in basket. Many others bounced back as spam, even though their spam score was always less than 1. Who knows how many were just junked in cyberspace along with the one I sent to myself.
I gave up.
There has to be another, better way.
Sandi