If inactive subscribers receive an endless sequence, start by preserving one representative example. It gives the investigation a concrete reference and makes the eventual correction easier to judge.
Find the likely cause
There is no stopping condition.
Treat this as an explanation to verify against the actual work. Look at the input, the relevant decision, and the final result together. If the evidence does not support this diagnosis, investigate the mismatch before applying a convenient but unrelated fix.
Make the targeted correction
Set a finite sequence and route nonresponders according to the list's preferences and policies.
Reactivation works best when it acknowledges a relevant reason to return instead of treating inactivity as disinterest alone.
Check that the repair worked
Verify that silence does not trigger repeated loops.
Repeat the check on the final version that the reader or customer will encounter. An approved draft, a preview, and a published result can differ; the acceptance decision should concern the version people actually use.
Prevent the next related failure
A separate issue to watch for is this: reactivation messages target active customers. Reconcile purchase and engagement records before building the segment.
Monitor the useful outcome
Measure returning qualified customers and negative responses by inactivity segment.
Keep a short record of the original symptom, the evidence behind the diagnosis, and the result of the acceptance check. That record makes the solution reusable when the same condition appears again, without assuming that every superficially similar problem has the same cause.