Quarantine (form spam)

In form spam handling, quarantine means holding a suspicious submission aside for human review instead of deleting it. The submission is not delivered, but it is not gone either - it sits in a labeled queue where someone can look at it and decide.

The alternative, silent dropping, has an ugly failure mode: no spam filter is perfect, and when a filter that deletes gets it wrong, a real lead disappears without a trace. Nobody is notified. The visitor believes they reached you; you never know they existed. On a lead-generation form, one false positive can quietly cost more than months of spam ever would.

Quarantine reframes the economics. A filter that quarantines can afford to be aggressive, because the cost of a false positive drops from a lost lead to a few seconds of review. It also produces a feedback loop - reviewing the queue shows you exactly what the filter is catching and whether its thresholds are tuned correctly.

SheetLink Forms is built on a quarantine-never-drop rule. Content heuristics (link stuffing, disposable email domains, empty payloads), the sl.js timing signal, and the per-form strictness dial (loose, normal, strict) all route suspicious submissions to quarantine for one-click review - approving delivers the row to your sheet as if nothing happened. Only the honeypot marks spam outright; nothing is ever silently dropped.

The reasoning behind the rule, and the rest of the spam stack it sits in, is laid out on the security page; the delivery pipeline it feeds is on how it works.