Computer programmers don't speak and write only English. I work with some Japanese programmers, and they definitely tend to use their native language a lot.

However, I am happy to note that the new version of Vico no longer suffers from this flaw. It can now open and edit files containing Japanese text.

Well, I guess I understand where you are coming from, but I really do think Thunderbird is garbage. It's a horribly, horribly buggy mail client (a client has 100+ installations with which I have some significant experience). Even without those killer bugs, it has a horrible cross-platform UI, it is slow, and I think its existence harms humanity. Apple Mail is much better than TB, in my opinion, and so is MailMate (already).

This discussion has kind of exploded beyond the scope of what MU is good at, but two points for web-searching posterity:

1) IMAP has no disadvantage whatsoever compared to POP. The only valid reason for POP's continued existence is "I, my mail software, or both do not know how to use IMAP." IMAP can do everything POP can do, and then a whole lot more also. You don't have to leave your mail on the server if you don't want. Although kind of weird, since a professionally managed mail server is far, far less likely to be compromised or lose data than your personal machine, you can use IMAP with the exact same workflow as POP. Download your mail to one PC and have it removed from the server. Or, you can choose to take advantage of its far more powerful design. POP is obsolete technology, but mainly 'good enough' to stick around, and impede human progress.

2) The new Lion Mail.app is shiny and iPadtastic, but aims at the less technically competent user. MailMate is aimed much more squarely at more advanced users. You will not see powerful searching and filtering coming to Apple's mail client--more likely, you will see those kinds of features reduced over time, as they confuse people with low computer literacy (which is, after all, most people). I wouldn't even be surprised to see Apple remove the capability to have multiple viewer windows open at the same time. As Apple expands its reach into the less-capable user tiers, it is all the more important to have high-productivity third party alternative apps, like MailMate.