I don't know of any Universal platform AutoResponder systems, (that's what these apps are called...) but considering the low cost of a good system like
aWeber (the one I use and it does EVERYTHING) it makes no sense to manage your lists on site.
The main reason NOT to manage your own list though, is the likely possibility that errors in the administration of your mail program can easily get your company's IP address BLACKLISTED.
The main reason a business owner would want to use an "in house" system, is to make the porting of an existing customer list easier.
FWIW, any company that will let you load a list into their system, without forcing confirmation by the e-mail address owners, WILL DESTROY YOUR BUSINESS, and ALREADY have a reputation for SPAM.
Lastly, e-mail marketing is NOT spam. But spam IS SPAM. That's why the system you use is so important. You should never NEVER send marketing messages to folks who have not opted in to receive those messages.
It's is either marginally legal, and often blatently illegal... Federal CANSPAM laws MUST be followed, even with a legitimate list. Mailing to folks who have ASKED for your messages, if the messages are not CanSpam compliant, can still end up causing you big trouble.
Bottom line... get someone who can explain this to your boss to explain it. This is NOT a small issue.
As you know, proper management of communications with existing customers can EXPLODE your revenues. There is only one way to do this with e-mail. The legal/right way.
SPAM SUCKS
