Sortd - Rated the #1 App for Gmail
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Drag for Gmail - Transform Gmail into organized To Do lists (like Trello)
Mailbird - Mailbird is the best email client for Windows 7, 8 and 10
Get My Receipts by cloudHQ - Organize your receipts in one click
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.