We are looking for a new ESP to test. We are working on optimizing our deliverability and are interested in trying various ESPs. Our mailing list is ca. 3m, all opt-in. We are estimating to send about 3-5m e-mails a month. We need an ESP with solid deliverability and that is used to third party offers. We do not e-mail anything in borderline spammy verticals, such as casino, gambling, adult, binaries, etc.
This maybe basic however here you go
1.activecampaign, it seems you can segment lists without 3rd party tools
2. Aweber+awprotools(awpro for segmenting) (everyones' standard issue go to esp)
3. Getresponse
4. Madmimi
Hope that helps to give you some options