I use phpList, we've had some problems but all in all it's been good. Is it the "best"? possibly not, but I've tried well over a dozen and I always end up back here. A licensed option that looks really interesting is Oi! Sarah
Sarah said: I've been thinking about trying it. What kind of problems did you have? What do you like about it? What don't you like about it? Best Regards, Steve MacLellan
I just started using phpList too -- haven't had any problems so far. It's got a pretty nice interface and it's pretty easy to find answers to questions through their forums. Good luck.