How to setup IMAP backend in Rails 5?

I have a rails 5 application and I have stored emails in mysql database.

What I want to do:

• I want to setup an IMAP backend in my Rails 5 application
• So that, users can use android and desktop email client to connect to my rails app
• And sync emails from my database to their email app (like gmail app)

• I want a very lightweight solution
• If no solution is available, may be, I will build it myself.

So, any suggestion / tips / documentation / tutorial is highly appriciated.

Thanks.