When using end-to-end encryption (E2EE) technology like OpenPGP, email will still have some metadata that is not encrypted in the header of the email. Read more about email metadata.

OpenPGP also does not support Forward secrecy, which means if either your or the recipient's private key is ever stolen, all previous messages encrypted with it will be exposed. How do I protect my private keys?

Rather than use email for prolonged conversations, consider using a medium that does support Forward secrecy.

Recommended Instant Messengers