Chrome/Safari: Streak, an email organisation suite for Gmail, unveiled message tracking today. Now, it integrates with Gmail (or Google Apps), pops up a message to let you know when a message has been read, and offers a timeline view so you can see who's read it, when and on what devices. Best of all, it's free.
The new tracking feature allows you to track unlimited messages, completely for free, and the whole thing blends nicely into the Gmail experience. You can toggle message tracking on and off easily from your inbox by clicking the eye next to each subject line, and you can even search across mailboxes for tracked messages using "has:tracking" as an operator. When a message you've been tracking is opened, you'll get a little notification in the lower corner of your window with who opened it and the type of device they're reading it on. You can even open a more detailed timeline view with more detail on when they opened it, a map that shows you where they're located, and any other people who opened it that the message may have been forwarded to.
Streak is actually a feature packed CRM and productivity tools for Gmail and Google Apps accounts, and the folks behind it are also responsible for the previously mentionedSecureGmail extension for encrypted email. Today's update adds message tracking to their core suite of email tools, which also includes things like delayed sending, auto-message organisation (into "boxes," which you can use for automatically organise specific projects without having to use labels or filters), and "snippets," a faster version of Gmail's own canned responses. Hit the link below to learn more.
Unlimited Tracking in Gmail [Streak]