I don't know... I've tried The Bat! multiple times, and while I will agree that it is an excellent overall email client with by far the most impressive feature-set in the entire email-client market, I find it very frustrating to use with the IMAP email protocol. I don't know how many of you use IMAP, but you will probably be bound to agree with me if you do. I wish I could use The Bat!, really. I've always been a great fan of Thunderbird, and still use it as my only email client, but recently I've found more problems with it than ever before. I desperately need a "check mail before send" option, and Thunderbird does not support this to my knowledge. Because of this, I am now stuck with having to restart Thunderbird every time I want to send mail! Talk about pain... just because that little option is missing, I can only send mail this way. For some reason, all the "send pending" or "send unsent" mail simply does NOT work in Thunderbird. I click on the button and it's as if the button to do so points nowhere. I will see if I can find extensions that will solve these problems for me, but isn't it a pain if you have to look for extensions that will fix something so fundamental?
Having said that, I wish I could figure out how to use The Bat! effectively with IMAP, but I'm afraid the boys over at Ritlabs will have to do some work on The Bat!'s IMAP backend.