Sortd - Rated the #1 App for Gmail
Roundcube - Web-based IMAP email client
Drag for Gmail - Transform Gmail into organized To Do lists (like Trello)
Mailo - Mailo is an email client where you can send and receive emails to and from anyone with an email address.
Get My Receipts by cloudHQ - Organize your receipts in one click
Mailpile - Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.