Do you use Lttrs daily? I'm wondering if it works in practice (even when using non-standard setup) or if it's just a proof-of-concept (that'd mean it may take some time to mature).
No I don’t use it daily. It can’t even send emails yet and you have to set your login credentials at compile time. I got frustrated having to deal with HTML emails and now I’m waiting for the servers to mature a bit. And honestly also for dovecot to announce support. I mean I love what the fastmail+cyrus team is doing; but if Dovecot is not going to support it, it is probably not worth it to build a JMAP-only MUA.