If you suddenly stopped receiving followups from us, or have never been able to receive a followups from us, there is a 99.9% chance that a spam filter is preventing your followups from arriving. We go to great lengths to ensure our followups are able to be sent from our servers on time and successfully deliver many thousands of reminders each day.
The remedy for this varies depending on your email service provider. The simplest solution is to add email@example.com to your address book or whitelist. You can also search for all emails from FollowUpThen (including any spam folders). You can also try some of the ideas listed here.