How a QR domain allowlist actually protects you
An allowlist is a simple promise: QR codes your organisation publishes may only point at domains you have approved. That sounds modest, but it closes a real failure mode. Campaigns accumulate redirect services, agency-owned domains, shortener links, and microsites that nobody remembers. When a domain lapses, an attacker can re-register it and inherit every printed code that points there. A reviewed list of approved domains turns that slow drift into a visible decision: if a domain is not on the list, the code does not ship.
The hard part is not the list; it is the ownership. Every entry needs a named owner and a reason, even if that record lives outside this tool in your own tracker. An entry nobody owns is an entry nobody will remove when the campaign ends. Review the list whenever a campaign closes, a domain is retired, or a vendor relationship changes, and on a fixed schedule as well. Quarterly suits most teams. At each review, confirm that every domain still resolves to the site you expect — a domain that now serves a parking page or someone else's content has already failed the test.
Subdomain matching is the decision most teams get wrong. Allowing subdomains of a domain you fully control is reasonable: your own team runs every subdomain. Allowing subdomains of a large shared platform is not, because other people can create subdomains there — your approval would extend to strangers. Keep subdomain matching off by default, and list each subdomain you actually use. The extra entries cost nothing; the blanket permission can cost a great deal.
An allowlist is also not a safety verdict. It says the domain is approved, not that the page is safe. An approved site can host a compromised page, a misleading form, or an open redirect that bounces visitors elsewhere. Pair the list with content review of the pages you link to, HTTPS everywhere, and monitoring that notices when a linked page changes. Treat the allowlist as one gate in a chain — the gate that stops the obvious mistakes, like a code pointing at a personal file-sharing link or a lookalike domain a tired campaign manager typed from memory.
Finally, make the workflow kind to the people who use it. If adding a legitimate domain takes a week of approvals, teams will route around the list with shorteners and personal domains, and you will have less control than before. Give campaigns a fast, reviewed path to add a domain with an expiry date, and an equally fast path to remove one. The goal is a list that reflects reality — every entry owned, current, and checked — not a longer list.