SendRecurring - SendRecurring allows you to setup, send, and maintain scheduled email reminders.
docassemble - docassemble is a free, open-source expert system for guided interviews and document assembly.
Recurrr - Send recurring emails
Knackly - Generate contracts, emails, or other documents of any complexity by automating your knack for doing...
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.
HotDocs - Template-driven, automated document & form assembly software