Ugh. Rainloop has been on my "to-port" list for sandstorm.io but I hadn't noticed the license. If I want to make this available as a "free" package that can be installed on an open source platform, but I also want to sell hosting for that platform, am I using it for my own commercial advantage and thus violating the license? Who knows?

Guess I'll stick to mailpile and roundcube.