I have tried many different bulk email tools, but none of them fully satisfied me. Except of "Atomic Mail Sender" from AtomPark. With Atomic Mail Sender i can compose personalized HTML messages and send it directly to all my customers - fast and reliable (what is the most important for me).
And it has friendly interface, ability to collect e-mail addresses from different file formats, make custom message headers and other. It is so simple to use, that everyone can use it without any problems.
All i can say is: amazing speed, amazing results!
One of the best investments in my life!