Bulk mail service provider - regular job

We normally do our mail marketing on our own dedicated server, but we are disappointed with the pricing. We send out around 15,000 emails a time. We have a Interspire Email Marketer license which you can use but if you don't like it you can use yoru own software. We would appreciate some statistics per mailing, and some promise of availability as we don't know always too much in front when we want to send out. We plan to send out regulary, but sometimes it will be once a week, sometimes 10 times. Our list is clean, never had too much problems with it, but you should be experienced with lists which are not clean at all. We would appreciate if we can send out from several domain names (per campaign), we have a dedicated DNS server in case you need to set up any zones. Please PM me with your masterplan and prices.