Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
Mailspring - Mailspring is a mail client for Mac, Windows and Linux.
IrfanView - IrfanView ... one of the most popular viewers worldwide.
Geary - Geary is an email application built for GNOME 3.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.
Airmail - Airmail is a lightweight and lightning fast mail client for Mac.