Yeah, that's the dirty hack I was referring to. I don't need to tell an smtpd "now's when I expect not to have an Internet connection", which this method relies on, and could happen as I walk into another room and lose WiFi. I just give it mail to deliver, and if it doesn't work it keeps retrying until it works (with configurable backoff and a setting saying when to give up for good).

Yup, I see where you're coming from. I've actually gotten used to mu4e's queuing behavior, and just leave it on all the time. For one thing, I like having a chance to edit/delete mail after hitting send (sort of like gmail's "undo"), and for another, I like the satisfaction of having a dozen or so messages sent all at once at the end of an email session.