A beautiful, fast and fully open source mail client for Mac, Windows and Linux. - Foundry376/Mailspring

Tests DMARC, SPF, and DKIM configuration

There are a number of solutions out there that allow you to back up your Google mail, but all of them have some significant shortcomings. That's pretty surprising given the popularity of GMail. BaGoMa aims to address all (or most) of them.

GPGee is a shell extension for Windows explorer that acts as an assistant for using PGP. It integrates itself into the context menu that appears when you right-click on a file and adds a new menu with functions to allow you to sign and/or encrypt files.