"The Bat!"? It was very good in POP3 times, then lack proper IMAP4 support for several years, but now authors claim that IMAP4 support is first-class. It is v

"The Bat!"? It was very good in POP3 times, then lack proper IMAP4 support for several years, but now authors claim that IMAP4 support is first-class. It is very old (first release in 1997) client with very-very old-skool features, like different templates with multitude of variables (and not only one option "where to place your signature") and rules to apply them (you could have different templates for different correspondents, you have different templates for new message, reply, reply to all and forward, etc, etc, etc). Built-in filters are rather good too, with a lot of automation. But it looks dated, and HTML support is not the best. And there is no manage sieve client. Edit: Windows only.