When you add an account in Thunberbird desktop, it sends your domain to Mozilla. This is namely done for autoconfiguration (populate server names and ports). T

When you add an account in Thunberbird desktop, it sends your domain to Mozilla. This is namely done for autoconfiguration (populate server names and ports). The problem with this is that it's just a dumb database (it doesn't check SRV and TXT entries) and as such, the database should really be client-side. The entire thing is just a pretext so that they can collect of all mail domains used by users. This isn't very Privacy-friendly.