SendRecurring - SendRecurring allows you to setup, send, and maintain scheduled email reminders.
Mailshake - Mailshake lets you build your professional network through a smart and intuitive approach to cold emailing.
Recurrr - Send recurring emails
Instantly - Build your own infinitely scalable cold email outreach system with Instantly.
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.
Snov.io - Sales engagement on autopilot.