Mailspring does something like that. I personally prefer people selling me yearly licences that do not call home, if a one-time is not possible. Depending on th

Mailspring does something like that. I personally prefer people selling me yearly licences that do not call home, if a one-time is not possible. Depending on the market you target, people might not like sw trying to call home (every adobe software ever?). My firewall would block and report it anyway.