BlueMail - BlueMail is an email management app for Android, iOS, and Windows.
Mailtrack.io - The best email tracking solution I've found. Free
Junk Email Filter - Junk Email Filter is a front end spam filtering and virus blocking service for email servers.
ReadNotify - ReadNotify enables the user to know when email is sent and the reciever reads the email.
Covideo - Covideo is a Video Email Platform for Businesses that enables companies to communicate quickly and effectively with their customers.
Bananatag - Find out what happens to your emails after you press send! Add email tracking, attachment tracking, email scheduling and templates to your daily emails.