Boomerang's email follow up for Gmail can help you keep track of important email threads, integrated seamlessly into your inbox.
Loving Boomerang. Best inbox management tool for Gmail I've found.
One of Boomerang’s most powerful features is tracking responses. When writing an email, you can set Boomerang to give you a reminder if you don’t get a reply after a certain amount of days. If the message comes back to your inbox without a response, you can then react by sending another email to follow up.
You can schedule your follow-up message as you're writing the original email. If the person replies to your original email, Boomerang will detect the response, and will not send the second email. If they don’t reply, Boomerang will send the follow-up message automatically, without you having to think about it.
Boomerang! Where have you been all my life?
Sam Grobart, The New York Times
Boomerang for Gmail. First off, if you don’t have it, stop reading this and go get it. Right now. There’s absolutely no other extension that will add this level of function to your Gmail.
Brad McCarty, TheNextWeb