A popback is a timed follow-up step for referrals that haven't been resolved yet — it automatically brings a referral back to your attention after a set number of days, instead of it silently sitting unanswered.
You configure your organization's popback sequence under Organization → Manage → Popbacks.
Each popback step has:
A background check runs hourly. For every active (non-archived) referral that's still moving through its sequence, it checks whether enough time has elapsed since the last update for the next step to fire. If so, the referral is flagged as a priority again (so it surfaces back on the dashboard) and, if that step is configured to, gets archived or deleted.
Steps run in the order you add them — put your earliest (shortest Time) follow-up first.
Separately from the popback sequence, Default Message for New Referrals sets the copyable text shown the moment a referral first arrives, before it's reached any popback step.
See also: Copyable Text & Markdown, The Referrals Dashboard.