Let's do more Q&A!
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QUESTION: Will you put more effort into feature parity with MS Outlook so Thunderbird can connect out of the box to exchange servers without IMAP support?
ANSWER (via @ryanleesipes, Thunderbird Product Manager): This is a complicated topic. We are looking into the best way to better support Exchange/O365 users. The problem is that Exchange/ActiveSync is not an open standard and thus, even if we implemented support, Microsoft can arbitrarily break us at any time.