Bitrix24 - Bitrix24 is a free (for small businesses) social enterprise platform. It is a united work space which handles the many aspects of daily operations and tasks. Create your own social intranet in minutes!
SendRecurring - SendRecurring allows you to setup, send, and maintain scheduled email reminders.
VOGSY - Professional service automation tool built on Google G Suite
Recurrr - Send recurring emails
Office Timesheets - Professional Services Automation
FollowUpThen - The simplest way to schedule an email reminder