Email Checker

Select the tool of your choice:

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

An email checker is a tool that verifies if an email address is valid. It means that if you write to this address, your email will be correctly delivered and will be read by a real person. Deltadromeus offers several email verification services. Just select the one that suits your needs. And if you want to understand how it all works, you are in the right place, we explain everything.

Check if email is valid

There are two things to do to check if an email is valid. First, a valid email address matches a specific format. It is a string of characters consisting of 3 ordered elements: a local part (for example "mickael"), the special character at sign ("@") and the domain name (eg "") which corresponds to the company hosting the mailbox. Regarding the allowed characters, the rules have been recently relaxed, but the email address must still meet specific rules and match a specific format.

But an email that matches this format is not necessary valid. Because what is also meant by valid is the fact that it really exists, in other words that it really corresponds to a registered and used mail account. Someone can invent a lot of email addresses, but if they do not correspond to an existing mailbox, it is useless to write to them because no mail will ever be received. A valid email is an email address that really exists. For this, it is necessary to check the email address validity. Thus, an email sent on a real email will be received and read.

The mail tester process

The job of a mail tester is to check an email address. This process is done in 2 steps: check the format of the address and check that its account exists. These steps are purely technical processes. The format responds to rules that can be controlled. Finally, checking that an email exists is an operation that can be done in a similar way to the operation of sending an email. To send an email conventionally, the computer software connects to the corresponding server (the domain name of the address), and in a language and established standards communicates with this server to transmit the mail. This communication is an exchange of data where the software transmits to the server various information such as the recipient (the local part of the address), the sender, the subject, the message, the attachments etc. Check an email account is similar to a simulation of sending an email. Like an email application, it is to connect to the remote server, to communicate with it, to exchange the agreed information but not to send a message. So no mail is actually sent, but the procedure ensures that the email address of the recipient exists for real.

Using an email verifier is the best way to check mail

Now, you know that to check an email address, you have to test the email in two big steps, a first on the format, and a second on its existence. These two steps are important and require technical skills. But the technical skills are not the only qualities to acquire, it is also necessary to have computer resources. One or more properly configured servers are required to communicate with the remote servers, generating increasing costs depending on the number of emails to check. Knowing how to check mail is certainly very interesting, but what is more is to know the audit tools that perform these verifications for you. You are already very knowledgeable when visiting Deltadromeus, as we offer the best range of email verifier: from the simple free online mail checker, to the on-demand verifier tool to use on your site through the mailing list tester. All of these tools use Deltadromeus's email verification to bring you the answer at the best cost. You choose!

Free email checker

Our free online mail checker tool called “Free Email Checker” is our most popular service. It offers the possibility to test the validity of an email address for free, simply by submitting the email in the online form available. Simple, fast and free! If you have been provided with an email and you are not sure of its validity, this service is for you. In 1 second, it determines whether the submitted address is valid.

Bulk email checker

For companies that need to check a large list of emails, “Bulk Email Checker” is the flagship product. It is available entirely online in your Deltadromeus account. You upload your file (your excel file or csv file containing the list of emails to check), wait a few moments for the email list verification, and you finally download your file that now includes the proven validity of each email address, one by one.

On-Demand email checker

For websites, web application and mobile application that must test the email address of their many visitors, “On-Demand Email Checker” is our on-demand mail verification service, available in the form of a simple API to call as a webservice. This product makes it possible to integrate email verification into its application, in the most flexible and open manner.

On-Site email checker

For websites that want to check emails submitted on one of their web registration forms, “On Site Email Tester” is the ideal solution. This product is added to your site very simply, as a plugin for wordpress sites or as a script for other sites. It does not require any web development. Once added, this tester tool automatically checks email for each submitted form and automatically asks visitors who made a mistake to edit their email. So no more email address is lost, you enjoy all your subscribers and can write to them without worry!