Comment by tredre3

I thought so too because 364 days of the year I will average 0 sent but that one other day I might have a conversation and I don't want my messages to be blocked when I reach 21.

Thankfully they allow some margins and after that they just delay messages to the next day: https://www.migadu.com/pricing/#what-after-reaching-limits

So micro seems like a pretty good deal that I'm now considering myself!