Ryan Hoover- Founder, Product HuntBoomerang's most known for resurfacing emails in your inbox based on your settings (e.g. if recipient hasn't responded in X days) but it also has email tracking functionality. Separately, if you want to block people from tracking you, install this. 😊
Yoni Shechter- Founder at @FavorizeAppSuper simple add-on to Gmail, which I mainly use to return an email back to my inbox in X days so I can act on it. Also useful to send an email later at a specific time and date, and return to inbox if no reply from email recipient. While I wish Gmail just had it for free, I love it and gladly pay $4.99/month to make sure I'm organized and on top of things.