Reference
How Mail Slots Are Tested: Reading and Verifying Independent Test Reports
Air leakage claims are common in this category. Verified air leakage data is not. Most mail slot hardware has never been tested to any recognized standard, which means a claim like "seals tight" or "blocks drafts" usually reflects a description rather than a measurement. This guide covers what makes a mail slot test report valid, how to read its results, and how to distinguish independently verified data from an unverified marketing claim.
What Makes a Test Report Valid
A valid air leakage test report for a mail slot rests on four conditions. First, the testing laboratory must hold accreditation to ISO/IEC 17025, the international standard for the competence of testing and calibration laboratories, through a recognized accreditation body such as A2LA (the American Association for Laboratory Accreditation).1 Second, the report must identify the test method by its full standard number and revision. ASTM E283/E283M-19 is the current revision of the standard used for air leakage testing of exterior windows, skylights, curtain walls, and doors, and the mail slot hardware installed in them.2 Third, the report must state the pressure differential the specimen was tested at, expressed in pascals. Fourth, it must provide measured leakage rates in cfm per square foot, or the metric equivalent liters per second per square meter, separately for infiltration and exfiltration.
A stated leakage rate that cannot be traced to an accredited laboratory, a specific test standard revision, and a stated test pressure is not a verifiable performance claim. It is a number without the documentation that makes it checkable.
How to Read the Results
Air leakage test results describe movement in two directions. Infiltration is air entering the building through openings; exfiltration is air leaving the building through openings. A complete report states both, since a mail slot opening does not perform identically in each direction, and a specification or comparison based on only one direction is incomplete. Results are expressed as a rate normalized to the size of the opening, in cfm/ft² (or L/s/m²), at the specific pressure differential at which the specimen was tested. A rate reported without its test pressure cannot be meaningfully compared to a rate from a different test.
For hardware that seals from more than one location, such as a mail slot with both an exterior and an interior sealing component, a complete report shows results for each component tested individually, and for the components tested together as a paired system. Reporting only the paired result omits how each half of the system performs on its own, which matters for a project sealing an opening with only one component installed.
Independent Testing Versus Manufacturer Claims
Independent testing means the test was conducted by an accredited third-party laboratory, or independently verified through an accredited testing organization, with no financial stake in the outcome, rather than by the manufacturer's own workshop or an internal quality check. That distinction matters because a manufacturer describing its own product as tight-sealing or draft-resistant is making a marketing claim, while a manufacturer citing a specific report number from an accredited lab is making a claim that can be checked against a document. Neither is inherently false, but only one is verifiable by a third party who was not in the room when the test was run. When a specification or purchasing decision depends on air leakage performance, the second kind of claim is the one that holds up to scrutiny.
How This Applies to the Brass-Seal
The Brass-Seal is among the first mail slots independently tested to ASTM E283 for air leakage, with results verified by Intertek under Report No. T4376.01-301-44-R1, at a test pressure of 75 Pa. The numeric results and pass-or-fail outcome are published on the product page and on the ASTM E283 explainer, which covers what the standard itself requires. The full report, including the laboratory's complete methodology and data tables, is available by request. See the LEED and WELL Documentation for the Brass-Seal to see how this kind of data is used in a certification submission.
Key facts on how mail slots are tested:
- A valid test report requires ISO/IEC 17025 laboratory accreditation, an identified test standard and revision, a stated test pressure, and separately reported infiltration and exfiltration rates.
- ASTM E283/E283M-19 is the current revision of the recognized air leakage test standard for exterior windows, skylights, curtain walls, and doors, including mail slot hardware.
- Infiltration and exfiltration describe opposite directions of air movement and should both be reported.
- Results for a multi-component system should be reported for each component individually and for the system as a whole.
- Independent testing means the test is conducted or verified by an accredited third party with no financial stake in the result, which is what separates a verifiable claim from a marketing description.
- The Brass-Seal is among the first mail slots independently tested to ASTM E283, verified by Intertek under Report No. T4376.01-301-44-R1 at 75 Pa.
Frequently Asked Questions
What makes a mail slot air leakage claim verifiable?
A claim is verifiable when it can be traced to an accredited testing laboratory, a specific test standard and revision, a stated test pressure, and measured results for both infiltration and exfiltration. Without those elements, a claim cannot be checked against a document.
What is the difference between infiltration and exfiltration?
Infiltration is air moving into the building through the tested opening. Exfiltration is air moving out. A complete report states both, since performance is not necessarily identical in each direction.
Does a manufacturer's own internal testing count as independent verification?
No. Independent testing means the test is conducted or verified by an accredited third-party laboratory with no financial stake in the outcome, not by the manufacturer's own staff or equipment.
Can I compare two ASTM E283 reports tested at different pressures?
Not directly. Air leakage results are reported at the pressure differential used during testing. Comparisons are most meaningful when the products are tested to the same edition of the same standard at the same pressure.
Where can I get the full Intertek report for the Brass-Seal?
The full report is available by request.
Sources
- International Organization for Standardization, ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories; American Association for Laboratory Accreditation (A2LA).
- ASTM International, ASTM E283/E283M-19, Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Skylights, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen.
- Intertek, "BOTA Brass-Seal System, Air Infiltration Testing," ASTM E283, Report No. T4376.01-301-44-R1.