Right Inbox - Schedule Emails in Gmail To Be Sent Later
Seventh Sense - Seventh Sense helps marketers and sales professionals reach the people that make them successful using artificial intelligence powered email.
EmailPlayground - EmailPlayground provides solution to schedule and send emails with ease.
SendLater - Email scheduler for Mac Mail.
Zendesk Support Suite - Zendesk Support Suite is a tool that solves and emerges multiple tasks in one place.
SndLatr - SndLatr is a Gmail plugin that makes it easy to schedule emails to be sent automatically at a later time.