Next week and next article appears on the blog, so today I would like to explain what is an email verification in theory and how it works in practice. I’m not gonna dive deep into technical information, just indicate the most important parts of the verification. First, a quick primer.


A DNS is a Domain Name System that points a domain name, to a servers IP address. Your DNS server would ask the root for and the root would say: I know the IP address for the domain, here’s the IP address for the .COM DNS server. Easy, right? A DNS happens right here with 3 simple steps: you have your domain name, server that is associated with an IP Address, then you have your website files. I hope you get it. 🙂

Mail Exchange (MX) records are DNS records that are necessary for delivering email to your address. The MX record is used to tell the world which mail servers accept incoming mail for your domain and where emails sent to your domain should be routed to. You will not receive email If your MX records are not pointed to the correct location.

Simple Mail Transfer Protocol (SMTP) – is an Internet standard defining how email transmission should be done.

SMTP Server – is an email server that confirms to SMTP Standard, and is able to receive and send emails according to it.

Real time email address verification process

At Bouncer we verify an email address in a real time, in 3 simple steps:


Checking the syntax of the email address to verify if there is a point at all to continue verification, the most primitive way to verify an email address is to see if the address is valid or not. Why? Because we determinate if the email address has the physical properties. This is to ensure that the email meets basic criteria such as whether it contains an ‘@’ sign etc. Take an We notice that there is a local-part (“WinstonIsCrazy) and the domain (, it does not contain any crazy forbidden characters, and overall confirms to the format of an email address. While checking the syntax we can tell you if a string of characters meets the requirements of a valid email address, though it tells us nothing about whether or not the email address actually exists or not. Does the email address belong to a real person? If I send a message to that address will it bounce? For that point, we have to try a different approach and attitude to this case. If the syntax is correct, actually you get an information that particular email address is VALID.


The second step is checking if the domain is set up well to receive emails, and which Email Service Provider is responsible for managing emails. Here we verify the validity of the email domain (MX record). This prioritizes the delivery of email messages on behalf of the recipient’s domain to make sure the email domain can send and receive emails.


The last point is Asking Email Service Provider whether the address is deliverable or not. There is a short communication between servers. I would like to illustrate to you how we check it:

A: Ehllo!


A: Is there an email address:

B:please, wait and ask me in 5 minutes, I don’t know…

A:okey, I will ask you in shortly future..


A: Ehllo! I am asking once again, is there an address: ?

B: no, there is not

Communication completed

Now we know that the email address has a status: rejected_email, because Email address was rejected by the SMTP server, email address does not exist.There can be also a different case when the server answers you that there is the email address, so you are super happy and you know that you will send a message to a real address. I know, I know, you can not wait to start your email marketing campaign and verify your email list… so do it NOW!

So what should you do first?

  1. Sign up on our website:
  2. Upload your email list as a CSV file
  3. Wait for verification (we work with <3 so as soon as possible you will get the result)
  4. Download your results and enjoy your email marketing campaign
  5. Check out your results:

The most efficient and effective way to keep your email list clean and maintaining a good sender reputation is to use the email verification every time you send an email marketing campaign. Get it started, verify with Bouncer <3 Don’t hesitate anymore 😀