email marketing HOST (not lists, not spambots)

I'm looking for a hosted email marketing solution provider like emarketer (webvisions.com/emarketer). i do NOT want to buy a bunch of lists, or a spambot type of offering. i just want an online marketing application - hosted by a proper normal host. i hve my own client list, its not a big spam thing. i need to manage subscriptions, bounces, automatically. i don't want to buy my own email marketing software and find an ISP that will let me run thousands of mails per second.

just a hosted email marketing application online, i am thinking probably offered by a host. emarketer (at webvisions - above) is OK. i am looking for comparisons - anybody using something similar? I do not want to talk about the constantcontact thing - i know about that.