I use Green Arrow engine + studio, by the folks at drh.net, and it can do that very well. You can basically get a hook that will execute your arbitrary code for each contact - database lookup on a remote service, whatever. So you can build very complex newsletters that are totally customized to each recipient. And it is fast as can be (can pretty easily push 1M+ messages per hour if you have that much volume to send)
In order to take full advantage of it you need to be a developer though.
It's got great pricing too, esp. if you get their perpetual license and then run it on your own dedicated server (they set it up.)
In order to take full advantage of it you need to be a developer though.
It's got great pricing too, esp. if you get their perpetual license and then run it on your own dedicated server (they set it up.)