Repl.email was great while it lasted, but sadly is no longer in service. Replit has changed a lot since this project was created, and this already was becoming too hard to maintain as it was.
Check out the repl.email noticeboard here!
I started work on repl.email late 2020. My goal was to host my own email service - like gmail. However, in order to host this on replit, I had to think outside the box. Replit only allows you to open a single port for hosting a webserver, so I found two third-party services that I would use to make this work.
By taking advantage of their free API, I can link my account to the domain I own, and send emails out to anyone, anywhere. They also support additional features such as scheduled delivery up to 72 hours in advance, which I incorporated into repl.email.
Yet another free service, improvmx lets me forward all emails sent to my domain (repl.email) to a set of mailboxes. For the mailbox I used gmail, and sorted emails into individual inboxes.