Aweber rocks for WH activities. They can get most emails through the spam filters. If you're wanting to install a script on your own server and mail to whomever you want your best choice is AutoResponse Plus. There's cracked versions of this out there; otherwise the price is pretty steep and it only installs on one domain name. I've used SendStudio also but I didn't find them to be as good as ARP. Whichever one you use you will not get past the spam filters for Yahoo, Hotmail, AOL, etc. so your only hope there is to have the recipient whitelist you if they have one of these addresses. When I used to purchase opt-in leads I'd just make sure that none of the addresses I bought were for any of those big boys, and I did pretty well.