The maildir package provides an interface to mailboxes in the Maildir format.

Documentation can be found online here:
https://godoc.org/github.com/luksen/maildir

This is what I used as a reference:
- https://en.wikipedia.org/wiki/Maildir
- http://www.qmail.org/qmail-manual-html/man5/maildir.html
- http://cr.yp.to/proto/maildir.html