How does email verification work? A simple guide.

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Top questions about email verification

Curious about email verification? We have 24/7 support available to help out with any specific queries but if you need to simply get an overview of how it works, here's a rundown of the top questions - and straightforward answers.

How does email verification work?

It starts with basic syntax checks. In an email address there must be a beginning, an '@'  and a dot.domain. Once we're sure we're dealing with a real email address we can check it in more detail.

someone at realperson.pro Email Hippo

This stage also involves analysing the domain status, (DNS records) to make sure the domain exists and that a mail server exists and is set up correctly. (MX Records). Mail servers that are badly set up might be open to being used for fraudulent activity. 

SMTP and other sources build an email profile

Once syntax, DNS amd MX checks have been made, mail server communication begins. Email verification is a communication between computers - specifically one is a mail server. We 'ping' a mail server to check the status of the inbox associated with an email address. The response received should follow the SMTP rules (Simple Mail Transfer Protocol) and be coded accurately so that we can interpret the code to give results. At a very basic level, the response status tells whether an inbox exists and is in able to receive incoming mail. Some mail servers are also set up badly and they don't follow protocol responses. That can result in an email address reported as one status, when in fact it is another. Basic example - the mail server might say an email inbox exists when it doesn't.

Deep SMTP detailed responses and information about the mail server itself help to determine whether for instance, the mail server is set up to receive ALL incoming mail to a domain, regardless of whether a specific inbox exists. Mail servers set up like this are called catch-all servers.

Other results  as part of our checking process are more complex. For example, if an email is associated with spam, if it's on blacklists or whether it is a disposable email address. That's not information we get from the email server, we get that (and other results) from multiple sources that we either own or reliable third party resources that we check in with.

Role based email addresses '[email protected]' and '[email protected]' for example, are identified by checking the email against our lists of hundreds of role titles. We keep these roles up to date with new trends and also hold them in multiple languages.

There are details about response codes and results in this free results guide.

Do you send an actual email - will the person know I am checking their email address?

No. We don't email the address, we only shake hands with the server and perform other checks with other sources. Email verification shouldn't involve sending real emails.

How long does it take to verify an email address?

It depends on the server, the software and the infrastructure that's making everything happen. Checking an email address should take only milliseconds. That's why email verification APIs are used in sign-up forms. Checking an email address shouldn't ever impede an interaction. It's a tool to enhance user experience - not slow it down. We publish our API response times publicly. (We're oh-so-rapido by the way - at the time of writing our API is running at a 444 millisecond response time, returning 74 pieces of data about every email address.)

This question is related to 'How long will it take to check my list?' The answer to that is more complicated as will depend on the number of emails, server load, the unique domains in the list, mail server rules about the speed we can make repeated contact and other variable factors out of our control. 

The words email verification and email validation written in Email Hippo brand colours

What is the difference between email verification and email validation?

Nothing. We use either term to make sure we're reaching everyone who is asking the question. Since we started it in 2009, email checking was always 'email validation' when it was being described formally. Just a few years ago, verification took over in search engines as it's a term that gets used more in Asia, so we use that word equally now.

According to the Oxford English Dictionary;

  • Validation is the action of checking or proving the validity or accuracy of something
  • Verification is the process of establishing the truth, accuracy, or validity of something

Do you store data of all the email addresses you check?

No. That would be against the terms of our privacy policy and our data processing terms. We've been asked this more often lately, we think it's becoming an issue as some email validation services seem to be storing and using email data for other purposes. Results are cached for a short period of time so they can be downloaded, or for retrying if we're asked by mail servers to return with another query. 

How can I ping an email address?

This is a popular question for student projects and start-ups! We've written the code out to help on our free apps site. Here is the top article to help with this.

Any questions?

If you've got any questions about email verification, get in touch. We're always happy to help.

Useful links

Beginners guide to email verification

A guide to email verification results

How to ping an email address

A guide to email verification results - download

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