## A Validation Report Is Only Useful If You Act on It You ran your list through an email validator and got a report back. Most of the addresses came back valid, a chunk came back invalid, and then there is the awkward middle: catch-all, unknown, risky, disposable, role-based. The report is accurate, but it does not tell you what to do next. That is where many teams go wrong.
Some delete everything that is not marked valid and lose real customers. Others send to everything except the clearly invalid rows and wonder why their bounce rate is still high. Neither approach uses the information the validator actually gave them. This guide walks through the common result categories, what each one really means, and a practical decision for each: send, suppress, hold back, or recheck.
Different validation services use slightly different labels, but the underlying checks are similar, so the same thinking applies whichever tool you use. ## What an Email Validator Actually Checks Before looking at the results, it helps to know where they come from. A typical validation run goes through several layers: 1. **Syntax.** Is the address shaped like an email address at all? Missing @ signs, spaces, double dots, and illegal characters fail here. 2.
**Domain and DNS.** Does the domain exist, and does it publish mail exchange (MX) records that say where its email should be delivered? 3. **Mailbox check.** The validator connects to the receiving mail server and asks, without sending a message, whether it would accept mail for that specific mailbox. 4. **Pattern and list checks.** Is the address from a known disposable email service? Is it a role address like info@ or sales@?
Does it match patterns associated with typos, abuse, or traps? Each layer can produce a clear answer or an inconclusive one. A syntax error is definitive. A mailbox check depends on how cooperative the receiving server is, and many servers are deliberately vague. That is why every validation report has a grey zone, and why the grey zone needs its own rules.
## Valid: Safe to Send, Within Reason A valid result means the address has correct syntax, the domain accepts mail, and the receiving server indicated the mailbox exists. **What to do:** Send. Valid addresses are the core of your audience. Two caveats are worth keeping in mind: - **Valid is not the same as engaged.** A mailbox can exist and still belong to someone who has not opened anything from you in a year.
Validation tells you whether mail can be delivered, not whether it is wanted. Pair it with engagement data. Our guide to email engagement scoring covers how to rank subscribers by intent. - **Valid is a snapshot.** People change jobs, abandon inboxes, and close accounts. A result that was valid six months ago may not be valid today, especially for business addresses. ## Invalid: Suppress, Do Not Retry An invalid result means the address cannot receive mail.
The syntax is broken, the domain does not exist or has no mail servers, or the receiving server said the mailbox does not exist. **What to do:** Suppress it. Do not send, and do not keep retrying in the hope that it will start working.
Sending to invalid addresses produces hard bounces, and a steady stream of hard bounces is one of the clearest signals to mailbox providers that a sender is not managing its list. Keep invalid addresses on a suppression list rather than simply deleting them. If the same address is imported again from a spreadsheet, a partner file, or an old export, the suppression list stops it from going straight back into your sends.
One exception deserves a second look: obvious typos. An address like name@gmial.com fails validation, but the person behind it probably meant gmail.com. Do not silently rewrite it, since you cannot be sure, but if you have another way to reach that person, such as an account page or a phone number they gave you, ask them to confirm. Better still, catch these at the form. Our article on email typo correction at capture explains how.
## Catch-All: Deliverable Domain, Unknown Mailbox A catch-all (sometimes called accept-all) domain is configured to accept mail for any address at that domain, whether or not the mailbox really exists. When the validator asks about anything@company.com, the server says yes to everything, so the validator cannot tell a real mailbox from a made-up one. Catch-all results are common for business domains.
Many companies configure their mail servers this way so that messages to misspelled employee names are not lost. **What to do:** Do not treat catch-all as valid, and do not treat it as invalid. Treat it as a separate segment with its own rules: - **Use other evidence.** A catch-all address that opened or clicked a recent campaign is clearly real.
A catch-all address that came from an old import with no engagement history is much riskier. - **Send to it in smaller, controlled batches.** If you mail catch-all addresses, do it separately from your main campaign so any bounces are contained and easy to measure. - **Watch the results closely.** If a catch-all segment produces bounces or no engagement at all, tighten your rules. We go deeper on scoring these addresses in catch-all email domains: validate, risk-score, and decide.
## Unknown: The Server Did Not Give a Clear Answer An unknown result means the validator could not reach a conclusion. The receiving server may have timed out, been temporarily unavailable, refused to answer verification checks, or applied greylisting, which deliberately delays unfamiliar connections. Unknown does not mean bad. It means "not checked successfully." **What to do:** Recheck before you decide.
Run unknown addresses through validation again later, ideally a few hours or a day afterwards. A large share of temporary failures clear up on a second attempt. Whatever is still unknown after a recheck can be handled like catch-all addresses: held out of your main send and only mailed in small, monitored batches if other evidence suggests the person is real.
If a big portion of a list comes back unknown, look at the domains involved. A cluster of unknowns on one domain usually points to that server's behaviour, not to bad data across the whole list. ## Risky: Read the Reason Behind the Label Some validators group several warnings under a single label such as risky or do-not-mail, while others report each reason separately.
Either way, the reason matters more than the label, because the right action differs. ### Disposable addresses Disposable addresses come from services that create temporary inboxes, often used to grab a discount or a download without giving a real email. They may accept mail today and disappear tomorrow. **What to do:** For most marketing programs, suppress them or block them at signup.
If your business accepts them for a reason, keep them out of long-term nurture campaigns. ### Role-based addresses Role addresses such as info@, support@, admin@, or sales@ belong to a function rather than a person. They are often read by several people, sometimes forwarded to a ticketing system, and the person who signed up may not be the person who reads the mail. **What to do:** It depends on how the address entered your list.
A role address that a business customer deliberately used for invoices or account notices is legitimate for those messages. A role address that appeared in a marketing import is a higher complaint risk. Our guide to disposable and role-based email addresses covers the decision in detail. ### Possible spam traps and abuse flags Some validators flag addresses that match patterns associated with spam traps, or addresses known to report mail as spam frequently. **What to do:** Suppress them.
The potential downside of mailing a trap or a habitual complainer is much larger than the value of a single contact. Then ask how the address got onto your list in the first place, because traps usually point to an old, purchased, or scraped source. ## A Simple Decision Table Here is a practical starting point.
Adjust it to your own risk tolerance and data: | Result | Default action | Notes | | --- | --- | --- | | Valid | Send | Combine with engagement data | | Invalid | Suppress | Keep on the suppression list | | Catch-all | Hold or send in small batches | Use engagement and source to decide | | Unknown | Recheck later | Treat as catch-all if still unknown |
| Disposable | Suppress or block at signup | Rarely worth long-term mailing | | Role-based | Depends on source | Fine for requested account mail | | Spam trap or abuse flag | Suppress | Investigate the list source | The point of a table like this is consistency.
When everyone on the team applies the same rules, results become comparable from campaign to campaign, and you can see whether a change in bounce rate came from the list or from something else. ## When to Validate Validation is not a one-time event. The best results come from checking at several points: - **At capture.** Real-time validation on signup forms stops many bad addresses before they enter your database. See real-time email validation.
- **At import.** Any list that arrives fr
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