Check email validity

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check an email address for free online

check an email list

verify email address via a webservice api

live test of email address on a form of your site thanks to a plugin

It is very common to have to check that an email address is valid. It means making sure it really exists and is being used by someone. Deltadromeus offers several tools to check an email address, either online and free, or on demand on your website, or for a mass check of a list of email addresses. In all these cases, the test of email validity that is performed is divided into two major steps.

The validity of the address format

Firstly, an email address must follow established formatting rules. For example, an email address that ends with a dot, or that contains two consecutive dots, is not correct. To verify the format, the email address (example "") has to be cut into three elements:

  • the local part, located before the at sign (example "john94")
  • the @ sign, called "at"
  • the domain name corresponding to the email server of the company hosting this email (example: "")

These three elements are obligatory, indispensable, and each one must respect the rules which concern it, as the consecutive characters, the presence of unauthorized character, etc.

As of this crucial step of validation of the format of the email, it is already possible to affirm that a given address is incorrect. But of course, this is not enough, because when we want to check if an email address is valid, we also want to know if a real person owns it.

The validity of the existence of the mailbox

Secondly, to verify an email address validity, you have to check the existence of the corresponding mailbox. This is a test performed by a server like, able to connect to these mail servers and communicate with them in the same way that a software sends a real email. But during this communication, the test will only check if the email address exists in real, instead of actually sending an email to the recipient.

So no email is sent but we get the assurance that the email address is correct.

Now you know how to check if email is valid. But given the complexity and technical skills needed during the procedure, the easiest way is clearly to turn to an email address validator tool. This is good, we offer on 4 easy-to-use tools that perform this task for you, according to your needs. Whether to check the validity of a single email address immediately online and for free, check of a complete large email list, or a test on demand via an api to call from forms on your own website, you will find the service that suits your needs.

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