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

TouchStream - Drip campaigns for Gmail

Recurrr - Send recurring emails

Signature.email - A powerful visual drag and drop email signature generator paired with the easiest way to maintain consistency for your whole team.

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.

Elite Email - Drag & drop email builder for awesome newsletters