Boomerang for Outlook - Boomerang for Outlook offers email productivity tools to track, schedule and send mails at the right time.
Recurrr - Send recurring emails
Outlook4Gmail - Outlook4Gmail provides easy synchronization of your Outlook and Google accounts
Right Inbox - Schedule Emails in Gmail To Be Sent Later
Covideo - Covideo is a Video Email Platform for Businesses that enables companies to communicate quickly and effectively with their customers.
SendRecurring - SendRecurring allows you to setup, send, and maintain scheduled email reminders.