[aboardRat4]

mu4e, but I suspect that a local maildir is a poor choice anyway.

It's better to have a local cyrus running and connect to it by imap, with, say, gnus.

[rahimnathwani]

Well, it says its bidirectional, so perhaps you could run two instances pointed at the same local maildir, but at different IMAP servers?

[aboardRat4]

You can do the same with a local cyrus.