FollowUpThen - The simplest way to schedule an email reminder
Followup.cc - FollowUp for email is a lightweight productivity suite that keeps your conversations and tasks from slipping through the cracks. Set perfectly timed reminders that arrive at the top of your inbox, right when you need them.
Right Inbox - Schedule Emails in Gmail To Be Sent Later
Gmelius - Gmelius is the first collaboration platform designed for G Suite and your company's daily tools.
Tomba.io - Tomba is the leading solution to find and verify professional email addresses. Start using Tomba and connect with the people that matter for your business.
SendRecurring - SendRecurring allows you to setup, send, and maintain scheduled email reminders.