Email Address Checker

What each check means

• Syntax: the address follows the RFC shape, the local part is 64 characters or fewer, and the domain has a real top-level domain. Quoted local parts and IP-address domains are technically legal but useless for outreach, so we mark them invalid.
• MX records: the domain publishes mail servers. No MX means nothing can be delivered, so the address is invalid regardless of how it looks.
• Typo suggestion: the domain is within two edits of a well-known provider, for example gmial.com. Fix it before sending.
• Disposable: the domain belongs to a temporary inbox service. The address may accept mail for ten minutes and then vanish.
• Role-based: info@, sales@, support@ and similar. These reach a queue, not a person, and are the most likely to generate spam complaints.
• Free mail: gmail.com, outlook.com and other consumer providers. Valid, but a signal that this is a personal rather than business address.

Valid, Risky and Invalid explained

Invalid addresses fail syntax, sit on a domain with no mail servers, or use a disposable provider. Remove them; every one is a guaranteed bounce. Risky addresses will probably deliver but make poor cold email targets: role accounts, likely typos, or domains where the MX lookup could not complete. Valid addresses pass syntax and MX and carry no red flags.

maria.garcia@acme.com     Valid    syntax OK, MX found
info@acme.com             Risky    role-based address
john@gmial.com            Invalid  no MX, possible typo of gmail.com
test@mailinator.com       Invalid  disposable domain

Valid here does not mean the mailbox exists. Confirming that requires an SMTP conversation with the receiving server, which browsers cannot perform. Treat this tool as the fast first pass that removes obvious junk before you pay a verification service per address.

Why list hygiene protects your sending domain

Mailbox providers judge a sender by outcomes: bounces, complaints and engagement. A list with a few percent of invalid addresses produces a bounce rate that Google and Microsoft read as a scraped or purchased list, and they respond by filtering the sending domain, not just the offending campaign.

The safest setup is to verify before every send, cap daily volume per mailbox, and send from dedicated outreach domains that are separate from your company's primary domain. InboxOne provisions those secondary domains and mailboxes with authentication already configured, so a bad list can be isolated and retired without touching your main brand.

• Re-verify lists older than a few weeks; people change jobs constantly.
• Drop role-based and disposable addresses from cold sequences entirely.
• Watch bounce rates per mailbox and pause any mailbox that spikes.