Spam filter false positives: what a held enquiry really costs
A spam filter can be 99% accurate and still hold one real enquiry in ten. How to work out what those misses cost you, and how to measure a filter before you trust it.
HumainboxCommon problem
How to tell whether your contact form is actually working
A test submission proves exactly one thing: that a message sent by somebody who knows to go and look for it arrives. It says nothing about the ones you never see, and those are the only ones worth worrying about. Four questions cover the rest.
Where it breaks
Which one is it?
Work down the list. Each one takes less time than the one after it, and you can stop as soon as something matches.
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Where does each form deliver — all of them?
- Not the contact page form. Every form: the footer widget, the popup, the quote request on the services page, the one on a landing page from a campaign two years ago. Sites accumulate forms and nothing ever audits them.
- On WordPress, our plugin lists every form and its current notification address on one screen, free and without an account. Elsewhere, open each one in turn and write down what you find — the writing down is the point, because next year this same question comes up again.
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Does that address still belong to somebody?
- An address can accept mail for years after the person behind it stopped reading it. A forward to an ex-employee, an agency mailbox from a contract that ended, a group that three people muted.
- Send one message to each address from outside your own domain and ask the person on the end to confirm they got it — not you, them. That is the whole test and it catches more than it should.
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Is anything being filtered before it reaches you?
- The spam folder is the visible part. A rule at the mail server that quarantines or rejects leaves nothing at your end to find.
- Check the folder, then check the message trace or quarantine if your mail is on Google Workspace or Microsoft 365. Then look at why: see the page on form emails going to spam.
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How would you find out if it stopped tomorrow?
- This is the one you cannot answer by hand, and it is the one that actually costs money. A form that quietly stops looks exactly like a slow month. Most people discover it when a customer phones to ask why nobody replied — an average of several weeks later.
- Two parts. Our free check reads your contact page and tells you what it finds, no account needed. And running a week of dry run answers the part nothing else can: everything is delivered exactly as it is now, and at the end you get a list of what would have been held — so the first thing you learn about the filter is what it would have done, not what it did.
The test everybody does, and what it leaves out
Filling in your own form and watching the email arrive tests the one path you were already sure about: a message you wrote, from a browser you were logged into, to a mailbox you were watching, at a moment you were paying attention. Every failure that matters happens on one of the other paths.
1 in 5
contact forms a browser can see are invisible to a single static read of the same page — 94.3% found on WordPress, 21.9% on Squarespace. That is our own instrument's blind spot, measured and published, and it is the reason a check is a starting point rather than an all-clear.
From our study of 598 contact pagesWhere the setting lives
The exact menu path, per builder, with the field named.
Find out where your forms actually deliver
Our free check reads your contact page and tells you what it finds. No account, nothing installed, and nothing on your site changes.
Questions people ask about this
How often is this worth checking?
Once a year, and every time the site is rebuilt, a form is added, or somebody with an address on it leaves. A rebuild is the common one: forms are recreated and the notification address is retyped from memory or left at the theme default.
Can I tell how many enquiries I have missed?
Honestly, no — not retrospectively, and be wary of anyone who offers a number. Missed enquiries leave no record anywhere: the visitor submitted, saw a thank-you message, and went on with their day. You can only start counting from the point you start measuring.
Do I have to change anything to find out?
No. The check reads a public page and changes nothing. The dry run changes nothing either — every message is delivered exactly as it is today, and the report at the end is a list of what would have happened. Deciding comes after the evidence, which is the right way round.