e.g. here: http://web.archive.org/web/20110904002532/http://weblogs.moz...
""It may turn out to be very difficult to support all three layouts (classic, wide, and vertical) without making each of them diverge further from each other, which is just an extra maintenance burden."
Then I propose dropping one or two of them and making the remaining one or two work as well as is humanely possible."
It worked out of the box with PGP. It worked out of the box with my LDAP based address book (both read and write unlike Thunderbird). It also seems much faster to me.
That said, if you are on Linux, Geary (http://www.yorba.org/projects/geary/) is great open source email client, that's built ground up for conversation style mail.
I guess I've just really missed the point of email clients or something cause people still make them and people still use them.
You might say that is a lot of mail, an extreme case, but when you help people, have clients, customers, sell stuff, etc all communication should be saved in case.
If I had something digital that I really couldn't afford to lose, the first place I would turn is to Google. Same goes for security. They may have their AI bots peruse through my stuff so they can advertise to me but overall I would think data is probably safer in their hands than my own.
I know that's just my opinion. But they don't have a long record of losing data/being hacked.