Paperless-Home - Find your documents when you need them most. Paperless manages them so you never have to dig through piles of paper or chaotic folders on your PC again.
Mailspring - Mailspring is a mail client for Mac, Windows and Linux.
Teedy - Teedy is a lightweight document management system packed with all the features you can expect from big expensive solutions but still easy to use.
Geary - Geary is an email application built for GNOME 3.
Paperless - Developers and publishers of Mac, Win, and iOS productivity, home and office and writing software such as MacGourmet, Paperless, MacJournal and many more. Based in MN.
Airmail - Airmail is a lightweight and lightning fast mail client for Mac.