I have been going over YouTube watching videos on eMail encryption and everyone seems to explain it from a different perspective. Some do it for a CompTIA exam while others just provide a primer. Here is what I understood:

Step1: You compose an email that you want to send. Without encryption, it will be simple ASCII text that will be visible to anyone along the way.
Step2: You generate a digital signature to make sure that nobody gets to re-transmit your email and claim it was you. Digital Signature is generated using Sender's private key which is usually a hash of the password and is then combined with the original message to form one long hash string. These signatures are one-time-use-only and a new one is calculated for every email.
Step 3: You encrypt the compose of your email using Receiver's public key so that the only person who can read it is the intended receiver using their private key
Step 4: When you hit the send the email, what is transmitted now is gibberish to everyone apart from the intended receiver who will decrypt is using their private key
And there are various ways to do it like PEM, PGP, etc.

Correct me where I am wrong or refine where necessary.