SendX.io - SendX (https://sendx.io) provides remarketing and retargeting tools for web businesses. You can use popups, landing pages, email, web push notification, automation workflows and FB / Google retargeting to drive more revenue.
Mailtrack.io - The best email tracking solution I've found. Free
Nova Inbox - Personalize emails in seconds, right from your inbox
Unlimited Email Tracker - Track opens and clicks, set reminders and delays in Gmail
Mailblast - Email marketing on a budget using Amazon SES
MailTracker - MailTracker is a mobile email tracking solution.