I don’t believe this is currently supported:
I have an option in my mail server to set the IMAP/SMTP listener to request a client certificate during the TLS handshake, before password credentials are passed.
This adds an extra layer of security to connections, kind of a two factor auth, with the “something you have” being a certificate file imported to your client.
This authentication method is currently supported in some other clients like Claws and KMail, and I believe the feature is being developed for K9-Mail on Android.
I’d love to be able to turn on this extra security. Is there any possibility of eM Client adding support for X509 authentication in the future?