SendRecurring - SendRecurring allows you to setup, send, and maintain scheduled email reminders.

Laytr - Laytr is the easiest way to defer emails.

Recurrr - Send recurring emails

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.

NudgeMail - Write or Forward any email to NudgeMail.