How does email open tracking work?
Vocus.io inserts a tracking pixel into outgoing emails that you send. When your recipient opens your email, their email client will load that tracking pixel, thereby informing Vocus.io that the email was opened.
This is the oldest trick in the book. All the Newsletters and marketing promotions that you receive, whether from your favorite social network or your favorite retail store, will likely have a tracking pixel embedded to collect analytics on their marketing campaigns. Vocus.io brings this same capability to the individual user.