Sounds like it's only meta-data of emails, not actual content when TLS is used.

chrismeller · on Feb 5, 2019

When TLS is used there is no metadata either... server x talked to server y for a while, but what, if anything, happened we know not.

CWSZ · on Feb 5, 2019

>When TLS is used there is no metadata either... server x talked to server y for a while, but what, if anything, happened we know not.

Quite a bit of metadata really...

Client X: IP address

Server Y: IP address

Client X request: TLS parameters that can be analyzed through TLS fingerprinting

Server Y response: Hostnames supported by SNI

Server Y response: TLS parameters that can be analyzed thorough TLS fingerprinting

zaroth · on Feb 5, 2019

In this case running your own server works against you.