Email verifier

It checks the address's format, then whether its domain has mail servers at all, then whether it's a throwaway inbox. Last, it asks the domain's mail server whether the mailbox exists, the way a sending server would at the start of a delivery, and stops before anything is sent.

Yes. You sign in with your email, using a code rather than a password, and get 30 checks a day. Each check costs us money, and the sign-in is what keeps bots from running it.

A catch-all domain's mail server accepts mail for every address, real or not, and sorts it out later. So it can't confirm whether one mailbox exists, and no verifier can either. Mail to a made-up address there may bounce later or vanish. Send to a catch-all address only when you got it from a reliable source, such as their website or an email signature.

Bounces are one of the plainest signs of a careless list. Mailbox providers count them against your sending domain, so more of your mail goes to spam, mail to valid addresses included, and most outreach tools pause a campaign whose bounces climb. Checking addresses before sending keeps them low.

An address for a function rather than a person, like info@, sales@ or support@. It's usually valid, but read by whoever is on duty, so a cold email to one should say in its first line who it's meant for. Some sending tools also limit how many role addresses a campaign may contain.

Yes, occasionally: a full mailbox, a server that blocks your sending domain, or a mailbox closed after we checked. A valid result means the mailbox existed when we asked. For a large send, check addresses close to the day you send.