I wonder if there would be a way with https to store an encrypted mail
Short answer: No.
Long answer: SSL makes use of a temporary session key that is calculated between the client and the server at the time of the connection. Once the connection is over that key is (ideally) destroyed. If the email was encrypted with my session key when I sent it to the server (and somehow not decrypted by the server at this point) your session key that you create when you connect to the server won't do the job.
This is what S/MIME is for. The email body (and optionally some headers) is encrypted with a session key which is encrypted with your public key (rather than the server's key). Then it is sent through regular email channels. You receive the email and decrypt the session key with your private key, and use it to decrypt the message.