http://industrymailout.com is my vote. We use them quite a bit for numerous clients and haven't had any problems. Anything not present in their back end, they've built in. Anywhere from 1000 - 35000 mails without a hitch and an API.
i guess i didn't necessarily want shared. just something cheap for our clients. and since most of our clients are in vancouver, the hope was that it was close by so hops or latency or whatever were kept to a minimum.