Question About Encryption

Here’s the scenario:

What if I’m running a mailinabox on a server in Germany and accessing it in the US. So all my emails are essentially going through fiber optics in the Atlantic.
Now, a XKRE server is listening to emails being sent and received from and to my server, and storing that data.
Now, the data XK
RE has stored: is it encrypted? Can it be read?
Is PGP my second level of encryption in this case? Or the first level?
I have a feel SSL and TSL connections will make the regular mails unreadable, but just want to confirm.
Thanks!

Hello. Please see https://github.com/mail-in-a-box/mailinabox/blob/master/security.md.