Free Gmail add-in to remind about outstanding answers

Dear community, I am looking for a free tool that reminds me about outstanding answers to my emails. I am aware of Gmail's snooze features but do not like the UI as the button is not available when drafting an email. I know that these tools provide the functionality but their free versions have these limitations: RightInbox: 5 reminders/month Boomerang: 10 reminders/month Thanks for your recommendations!