Disposable Email Detected: This email domain is associated with temporary/disposable email services and may not be suitable for long-term communication.
Email Validator checks an address as you type it: structural syntax against the rules most providers enforce, screening against a built-in list of disposable domains, and typo detection for common misspellings of major providers. The address is processed in the page and is not transmitted or stored, which makes the tool safe for checking addresses pulled from a private customer list.
How to Use
Type or paste one address into the input field. Validation is debounced by half a second, so the verdict appears shortly after you stop typing; pressing Enter or the Validate button forces an immediate check. A green check with “valid” means no issues were found. A red result lists each issue, and when a known typo is detected a clickable suggestion appears — clicking it replaces the input and re-validates.
For Gmail and Googlemail addresses, the tool also shows a normalized form with dots and +tags removed, with a copy button. That normalized value is what you would compare against to find duplicate signups.
What This Tool Checks
The pipeline runs four distinct checks and combines their results into one verdict.
| Check | What it looks at | What it does not do |
|---|---|---|
| Structure | Exactly one @; non-empty local part up to 64 characters; non-empty domain up to 255 characters containing a dot; TLD of at least 2 characters | Validate the full RFC 5322 character set or reject unquoted spaces and other illegal characters |
| Disposable domains | A built-in list of roughly three dozen known throwaway providers, including subdomains | Detect every disposable service that exists |
| Typos | About two dozen known misspellings of Gmail, Hotmail, Yahoo, Outlook, Proton Mail, and iCloud | Catch misspellings outside that dictionary |
| Normalization | Lowercasing; Gmail/Googlemail dot and +tag removal | Rewrite other providers’ aliases or plus-addressing |
Any issue from the first three checks makes the overall result invalid, even when the cause is a policy decision such as a disposable domain rather than a syntax error.
Syntax vs Deliverability
It is worth separating three questions that people often collapse into one. Is it syntactically valid? This tool answers that. Could the domain receive mail? That requires a DNS lookup for MX records, which this tool does not perform — a domain can look perfect and have no mail server. Does the mailbox exist and is it monitored? That requires connecting to the mail server and, in practice, sending a confirmation message.
Because the check is local and offline-capable, it is a fast first filter, not a final authority. A passing address can still bounce; a failing address on the disposable list is intentionally rejected even though it would receive mail. For signup flows, use this as the synchronous validation layer and follow it with an email confirmation step.
A catch-all domain is a related trap. Some mail servers accept every address at their domain, so typo@yourcompany.com may be delivered even though no such mailbox exists. Structural validation cannot see this, and it is another reason a confirmation message is the only reliable proof that an address works.
Worked Examples
john..doe@gmial.com — the structure passes (one @, valid lengths, a dot, a 3-character TLD), so the verdict is valid, but the typo dictionary matches gmial.com and suggests john..doe@gmail.com. Note that the doubled dot in the local part is not flagged, which is the structural-check limitation in action.
user@mailinator.com — structure passes, but mailinator.com is in the disposable list, so the result is invalid with a disposable warning.
user@@example.com — two @ symbols produce “Email must contain only one @ symbol” and the check stops early.
user@example — no dot in the domain produces “Domain must contain a dot (e.g., example.com)”.
user@example.c — the TLD is a single character, producing “TLD must be at least 2 characters”.
user name@example.com — an unquoted space in the local part still returns valid, because the format check does not inspect characters. This is a known false positive.
Normalization and Duplicate Accounts
John.Doe+news@gmail.com normalizes to johndoe@gmail.com. Gmail ignores dots and everything after a + in its own addresses, so all such variants reach the same inbox, and treating them as one identity prevents duplicate registrations. User.Name@googlemail.com normalizes to username@googlemail.com; the domain is not rewritten to gmail.com, so a check that must catch Gmail and Googlemail duplicates should map both domains together. Other providers, such as Outlook with its own plus-addressing, are only lowercased and otherwise left alone.
Accuracy and Limits
The validator is honest about being a first pass. It does not verify deliverability, mailbox existence, domain reputation, or catch-all behavior, and it never contacts a mail server. The disposable list and the typo dictionary are fixed snapshots, so newly launched throwaway domains and novel misspellings slip through. The structural checks are intentionally light and will accept some addresses that the full RFC grammar forbids, including unquoted spaces and numerically named TLDs. Use it to catch the common, cheap mistakes instantly, and rely on a confirmation email for anything that matters.
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Frequently Asked Questions
Does a green result mean the mailbox actually exists?
No. A pass means the address is structurally well-formed and not on the built-in disposable list. The tool performs no DNS lookup, no MX record check, and no SMTP handshake, so it cannot tell whether the domain accepts mail or whether the specific mailbox is active. Only a delivered confirmation email proves that.
Why is a disposable address marked invalid when its format is fine?
Disposable-domain screening is part of the same issue list as format errors. When the domain is found in the built-in list, the tool records a disposable issue, and any issue makes isValid false. The address is syntactically correct; it is being rejected on policy, not on syntax.
Does the validator reject invalid characters such as an unquoted space in the local part?
No. Format checks cover the presence and count of @, non-empty and length-limited local and domain parts, a dot in the domain, and a TLD of at least two characters. They do not validate the full RFC character set, so an unquoted space like user name@example.com can still return valid. Treat the result as a structural test, not a character-level one.
What is the normalized address, and why did the dots disappear from my Gmail?
Normalization lowercases the whole address; for gmail.com and googlemail.com it also removes dots from the local part and strips a +tag suffix. So John.Doe+news@gmail.com becomes johndoe@gmail.com. This is how Gmail itself treats those addresses, which is useful for spotting one person who registered twice under variants.
Can I validate a whole list of addresses at once?
No. The tool validates one address per entry and shows a single verdict with issues and suggestions. For a list you would need to check each address in turn. The processing stays in the page, so pasting many addresses one by one does not send them anywhere.
How reliable is the typo suggestion?
It matches the domain against a fixed dictionary of about two dozen known misspellings of Gmail, Hotmail, Yahoo, Outlook, Proton Mail, and iCloud. Exact matches and subdomains of a listed typo are caught, and the suggestion is offered, not applied automatically. A misspelling that is not in the dictionary, such as a transposition in a company domain, is not detected.
Reviewed by the HandyTools Hub team · Last updated