Airtable - Airtable works like a spreadsheet but gives you the power of a database to organize anything. Sign up for free.
SendRecurring - SendRecurring allows you to setup, send, and maintain scheduled email reminders.
Creativity 365 - Cross-device content creation suite
Recurrr - Send recurring emails
Microsoft Teams - Microsoft Teams provides the enterprise-level security, compliance and management features you expect from Office 365, including broad support for compliance standards, and eDiscovery and legal hold for channels, chats, and files.
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.