Mailserver behind NPM

[FlorinBuffet]

Hi there
My mailserver currently has an own public ip and is routed around npm. He has it's own let's encrypt certificate that also gets used for encrypted email.
Therefor i need the certificate to be locally on the target vm.
I know there is no ssl passthrough, but is there another way to get the server to use it's own caddy ssl certificate (and is still able to generate it) while routing this over npm?
Best Regards
Florin