Mailtrack.io - The best email tracking solution I've found. Free

Outreach.Buzz - Outreach.Buzz helps people connect with bloggers and influencers in order to promote their content, increase their traffic, and reach the highest rankings in search engines.

ReadNotify - ReadNotify enables the user to know when email is sent and the reciever reads the email.

RELEX - RELEX provides solutions for retailers, wholesalers and manufacturers to optimize their supply chains.

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.

BluePlanner - Sales Planning, Trade Promotion, and Analytics Software for Consumer Goods Manufacturers