EmailPlayground - EmailPlayground provides solution to schedule and send emails with ease.
Right Inbox - Schedule Emails in Gmail To Be Sent Later
SndLatr - SndLatr is a Gmail plugin that makes it easy to schedule emails to be sent automatically at a later time.
Seventh Sense - Seventh Sense helps marketers and sales professionals reach the people that make them successful using artificial intelligence powered email.
SendLater - Email scheduler for Mac Mail.
GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!