A Minimal Email Client
Tangentially related: I really like the approach of mu [1]. Let other software (like mbsync) handle IMAP synchronization of a local maildir, let other software (like msmtp) handle sending, and focus on doing really good, flexible and efficient queries of the local maildir. Then you can build whatever thin, simple GUI on top of that.[1] https://www.djcbsoftware.nl/code/mu/