Boomerang for Gmail lets you control when you send and get email messages. It is available in Firefox, Chrome, and Safari.
Send an Email Later - Boomerang allows you to send an email right now and have it sent at the perfect time. Simply write your message as usual, then click on the Send Later button. Boomerang can be notified by using our handy calendar picker, or our text box which understands language such as "next Monday". We'll handle it.
The best reminders - Do you want a cleaner inbox but still keep track of important messages and important emails? Boomerang allows you to remove messages from your inbox until they are needed. Click the Boomerang button whenever you have an open email and select when you want it to be archived. Boomerang will archive your message. Boomerang will archive the message at the time you choose.
You can be reminded if you don’t hear back. There are times when you must follow up within a certain time frame after you have sent a message. You can choose to be reminded only if someone replies or all the time. This will ensure that you don't lose messages and that you never forget to follow-up with people.