The fix from a few hours earlier did what it was meant to: the dashboard could no longer trigger a live check of its own. What it hadn’t been asked was who does that job instead.
The fix that solved its own problem too well
Turning a page from “ask live every time” into “read what was last found” is right when the asking was the problem. But the live version, however clumsy, was also what kept the answer current. The dashboard now only read a cache, and nothing else had been given the job of filling it. The only other place that could was a page visited when something already feels wrong. So the cache stayed empty, and the dashboard honestly reported nothing, which a status light renders like a problem.
Confirming before chasing
The two services involved were checked directly and were fine. The issue was never whether mail worked, only whether the dashboard could hear about it.
Giving the job back, just less often
A small recurring task now does the checking that used to ride along with each visit. The dashboard goes back to only reading, and something else is responsible for keeping the answer recent.
A second, smaller room found while the light was on
A status-table column that had been empty now shows the port each service is bound to, read live. That also explained a long-standing false alarm in the security scan, which was flagging expected ports it had never been told about.
What actually finished
A dim status light now means what it says and is refreshed on its own, and the table answers the port question at a glance.