We have 3 high volume double-opt-in newsletters which go out each week. They are prohibitively expensive to go with a Constant Contact type of service as we push on average 3 newsletters out to 200k recipients a week. I have been using Sendblaster which for the money you can't beat but it's buggy as all get out, crashes all the time, constant database corruption. It's becoming a real issue. Do other people use similar on premises applications? Preferably web based.