Keep domain and mailbox separate
Read the exact definition used by your vendor rather than assuming all tools use “catch-all” identically. A domain attribute and a specific address observation are related but different pieces of evidence. Do not treat a more detailed label as an independently proven accuracy advantage.
Compare without false certainty
Ask what the service reports, which cases remain uncertain and what additional processing costs. Competing merchant claims may use different samples and definitions. This guide has not independently tested their resolution methods.
An internal decision note
Record the original category and the unresolved question. If your process requires a confirmed mailbox outcome, the record stays held until appropriate evidence exists. Do not send speculative messages just to test it, and do not automatically delete a legitimate relationship because the technical check could not settle the question.
Put it into practice
A practical comparison question is: “Which observation concerns the domain, which concerns the specific mailbox, and which remains unresolved?” Record the answer using the selected vendor's current definitions. Do not assume that every service's catch-all result has identical semantics or that a second confidence score eliminates uncertainty. In a fictional review, the team needs a definite mailbox conclusion before a particular downstream action. If the available result does not supply that conclusion, the correct workflow state is held, regardless of how persuasive the product marketing sounds. Another team may have a different authorised purpose and risk process; this guide does not set that policy for them. Preserve the original result and date so the decision can be revisited with new evidence. Do not use speculative sending, address guessing or repeated mass checks as substitutes for a documented resolution process.
Sources used for this page
These records support the facts and comparisons above. Merchant-controlled records are labelled so you can separate product claims from independent evidence.
- Bouncer API introduction — Merchant documentation · docs.usebouncer.com · Merchant-controlled · checked 2026-09-27
- ZeroBounce API documentation — Merchant documentation · zerobounce.net · Merchant-controlled · checked 2026-09-27
- Bouncer comparison discussion — Merchant documentation · usebouncer.com · Merchant-controlled · checked 2026-09-27