Because they still can't read your email, nobody can, even thought it is on their servers and crossing Swiss borders.
I'm at a loss. What a mess.
Of course this means that emails are only encrypted "in transit", that is, in the transmission from server to server, so you have to trust your provider.
On the contrary, PGP gives you end-to-end encryption, so you only have to trust your machine and your correspondent 's.