Thunderbird is trash, Postbox is not really getting updated and also it’s not fully portable. em Client looks childish and only supports very old S/MIME hashing algorithms, so … far from being secure.
Outlook is great but no… I want something more handy.
The other million clients which I tried out all missed basic functions, e.g. when I reply to someone the reply started at the top. Total fail. Or S/MIME was missing or PGP was missing or no HTML mode at all (sad).
Thunderbird for examble is portable, supports S/MIME and PGP (more or less) but no way to replace the ugly colored quote bar with the real quote signs “>” and “»” in HTML. I am sure not going to switch back to 1980 plain text ;)
Any ideas? But it seems there are no other Windows clients :(