My followups are getting bounced or deferred by my email provider.

Even though we have delivered millions of followups with a very high success rate, an email provider may still occasionally refuse to accept our reminders.

This may happen because the content of a followup triggers rules in a spam filter, or, less commonly, if one of our servers appears on a blacklist.

To ensure your FollowUpThen emails are not blocked:

  • Whitelist email is sent from
  • Whitelist emails coming from the domain
  • Whitelist emails with return-path
  • Whitelist our IP addresses. We use Amazon to send email. The IPs for this service can be easily found by running:  dig TXT +short| grep ‘v=spf1’

Improving our deliverability is something we continuously strive to improve on or end. For example, we recently (Feb, 2019) introduced a premium message dispatch service as well as a new set of reserved servers that we can closely monitor.

To see if any outstanding followups have bounced, visit your Pending Followups and click the “completed” filter to see all followups the system has tried to deliver.

Putting the right information in your inbox at the right time is one of our highest priorities. If you have any questions or concerns about deliverability please contact us.


If you suspect your email provider is blocking or deferring messages from FollowUpThen, please contact your email hosting provider or IT department and ask them to whitelist emails coming from FollowUpThen. This can be done as follows: