How to Check an Email Address Before You Send

Sending emails to invalid, non-existent, or disposable addresses damages sender reputation and causes high bounce rates. Verifying an email address before sending helps keep your communication clean and professional.

What makes an email address valid

• RFC 5322 Syntax: The mailbox and domain follow standard formatting standards with valid characters and structure.
• Live Domain Resolution: The website domain actually exists on global DNS servers and is active.
• Mail Exchange (MX) Configuration: The domain administrator has configured active mail exchange servers ready to accept inbound emails.
• Disposable Filter: The domain is not an expiring burner inbox created for temporary throwaway use.
• Mailbox Identity: Determining whether the address belongs to an individual person or an organizational role mailbox.

How the DocBrio checker works

The format check and the disposable domain check run in your browser. To see whether the domain has mail servers, the browser asks a public DNS service, and for that it sends the domain name only. The section on what leaves your browser, further down, explains this in detail.

Step by step email verification

1. Enter or paste the email address you want to check.
2. Click Verify Email Address or press Enter.
3. Read the result of each check and the estimated score.
4. Look at the suggested first and last name, which is a guess from the address.
5. Use the direct website link to visit the associated organization domain.
6. Review the detected email service provider, from Google Workspace to Microsoft 365 or custom corporate servers.

Used with these limits in mind, a quick check catches typing errors and dead domains before they turn into bounced messages.

What the result does and does not tell you

It helps to be exact about the limits. The checker confirms that an address is written in a valid form, that its domain exists and that the domain has mail servers. It does not, and cannot, confirm that one particular mailbox exists. An address such as a misspelled name at a large mail provider passes every check and still bounces. The score shown with the result is an estimate based on these checks. It is not a measurement of deliverability.

What leaves your browser

To look up the mail servers, your browser sends the domain part of the address, meaning everything after the @ sign, to a public DNS service run by Google, or to one run by Cloudflare if the first does not answer. Those services see the domain name and your IP address, as they do for any DNS lookup. The part before the @ sign is not sent, and DocBrio does not receive or store the address. The format check, the disposable domain list and the name suggestion run inside your browser.

Worked example: checking a sign up before replying

1. A customer enquiry arrives through your website form with the address sara.khan@gmial.com.
2. The checker reports either that the domain has no mail servers or that it belongs to an unrelated party. Look at the domain: gmial is a common typing slip for gmail.
3. Do not correct it silently and send personal details to your guess. If the form also collected a phone number, confirm the address that way.
4. For your form itself, add a second field that asks people to repeat their address, or send a confirmation link. That prevents the problem at the source.

Common mistakes

• Treating a pass as proof that a person will receive your message.
• Checking a purchased list and then mailing it. A valid format does not give you permission to email someone. Many countries have laws on unsolicited email, and mail providers punish senders who ignore them.
• Relying on the suggested name. It is derived from the letters before the @ sign and will be wrong for many addresses.
• Rejecting every role address such as info or sales. For a business enquiry, those are often the right contact.

When you need something else

To know that an address really works, there is one reliable method: send a confirmation message with a link and wait for the click. For large mailing lists, use the confirmed sign up process of your email service. This checker is suited to single addresses, such as catching a typing error before you send an important message.