[Dovecot] I'm the beginner and I want some help

Hello, I'm a software programmer and I work for a software corporation. We worked on dovecot for a while. We want to add some new functions to dovecot. For example, the mail stored on Mail-Server is plaintext, so we want to make it encrypted. As the documentation was not too much, and read the source code was too difficult for em. Would you give me some advice if I make this specialty as a plugin? Thank you!

WD David from China.