Based on our record, Followup.cc seems to be more popular. It has been mentiond 1 time since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
I'll update this if I find more. For now, this seems to be a partial solution. It's a Gmail add on (except I don't use Gmail) that adds reminders. The options when setting reminders include cancelling it if someone replies, and to remind everyone in the thread. If you combine those two, it seems like — if you use Gmail's web client and have $23/month you're dying to get rid of — a decent way to add the feature. Source: over 1 year ago
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
FollowUpThen - The simplest way to schedule an email reminder
Any.DO - The #1 task management app used by over 11 million people globally, Any.do is your free mobile and online task manager for Android, iPhone, Web and more.
Gmelius - Gmelius is the first collaboration platform designed for G Suite and your company's daily tools.
Microsoft To-Do - Task management tool
Right Inbox - Schedule Emails in Gmail To Be Sent Later