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What Is a Valid Email Address Format?
Daniel Gorbenko
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What Is a Valid Email Address Format?

What is a valid email address and how to distinguish it from an invalid one? Knowing this will help you use email for business, sales, and marketing purposes effectively and ensure that your sender’s reputation is good.

To help you get clear on this matter, the team of LeadsForce has prepared a simple, yet comprehensive, guide on a valid email address format. Read on to learn more!

Email Address Structure

Before we move to discuss valid email address formats, special characters or elements, and other details, it’s crucial to get clear on the email address structure.

So, what does email address look like?

Basically, every email address has three parts:

  • Local part (or unique address) - The username of every mailbox that comes before the @ symbol and is unique for every user.
  • @ (“at”) symbol - A special character that connects the username and the following domain part.
  • Domain name - A part that follows after “@” and indicates the specific mail server where a particular mailbox is located. It can be a specific mail service’s domain (e.g. or, if it’s a corporate address, it will typically indicate the name of the company and lead to its website (e.g.

Valid email address example:

Apart from this, there are also two additional elements of the email nomenclature:

  • .com, .net, .org, etc. - The ending of a domain.
  • Display name - The sender’s name that users see in their mailbox. For example, for the address, the display name would probably be Jenifer Still.

History of the Email Address

The first use of an email address took place in 1970 at MIT. MIT created an internal computer messaging system and used email addresses to define the users in that system. These addresses consisted of the user’s name, the @ character, and the name of a specific computer.

As the Internet was developing and becoming more common, the Domain Name System (DNS) was introduced. This expanded the number of locations where one could send a message.

Later, the first Internet Service Providers (ISPs) and email hosting websites were introduced. They started shaping online mailing the way we know it today.

All these events were changing and shaping the formats of email addresses. These days, there is a wealth of different email providers, which allows such a variety of addresses. And the possible uses for email are now broader than ever.

Special Characters and Punctuation

The email address format allows the use of special characters and punctuation elements in both parts of an email separated by “@”.

The local part should be under 64 characters and can include the following:

  • Numeric values (0-9)
  • Special characters, including # ! % $ ‘ & + * – / = ? ^ _`. { | } ~ (note that a dot (.) can’t be put at the beginning or end of the address and there can’t be two or more subsequent characters (..).

A dot (.), hyphen (-), underscore hyphen (_), and plus sign (+) are the most commonly used elements.

Examples of valid local parts:





Special characters and punctuation can also be used in the second part of the address. The correct email address syntax for the domain part can include up to 63 characters, have several parts separated by a dot, and contain:

  • Numeric values (0-9)
  • A hyphen (-), but this element can’t appear at the beginning or end

Examples of valid email domains:

Case Sensitivity in Email Addresses

When answering the question “what is a valid email address,” case sensitivity is worth a separate mention. Some people tend to start their email addresses with a capital letter, include uppercase characters in the middle of their addresses, or even use caps lock.

Does this change anything? The answer is no. 

The domain part is not affected by capitalization at all. The first part of the address, in theory, may be affected by the capitalization on some mailing servers.

Nevertheless, such cases are incredibly rare. Besides, the most common servers like Gmail or Postfix, are all case insensitive. Therefore, whether you send an email to:

  • Address@Domain.Com

or even


Your message will end up in the same inbox. So, there is no real need to care about the capitalization in email addresses on your mailing or business leads list.

Email Addresses to Avoid

Since we are talking about the use of emails for business or sales/marketing purposes, it’s worth noting that not all emails (even if they’re valid) are beneficial to your mailing list. There are two primary types of emails you don’t want to waste time on.

Role Addresses

A role account can look like sales@companyx or info@companyx. As a rule, such accounts aren’t assigned to a particular person but are handled by the entire department. Sending a sales, marketing, or introduction email to such addresses can lower your open rates.

Spam Traps

Sma traps typically correspond to a valid email format and might actually have real inboxes, so detecting them can be hard. But they are there to catch spammers and can really harm your campaigns. To avoid them, you should use trusted email verification tools that are capable of detecting spam traps.

How to Verify an Email Address Syntax?

Having invalid email addresses on your mailing list can cause many troubles. However, defining whether a particular email nomenclature is valid or not on your own is nearly impossible. Unless, of course, there is a notable mistake in, let’s say the name of the company or user.

One way to protect your campaigns from deliverability, bounce, and other issues is to use email verifiers or the best reverse email lookup tools. Such tools will help you detect invalid addresses on your mailing list and, thus, avoid sending emails to them.

But, there is also another solution. While verifying emails on lists that are already shaped can be pretty time-consuming, you can save plenty of time and energy if you collect ONLY valid emails in the first place. With the help of LeadsForce, you can find thousands of leads that match your ideal customer profile and collect their valid contact details without a hassle. By entrusting this task to LeadsForce, you can create effective and accurate mailing lists, and rest assured that you will never send emails to the wrong people or invalid addresses!

Daniel Gorbenko - Product Marketing Manager
Daniel Gorbenko
Product Marketing Manager
Daniel is a Product Marketing Manager with more than 4 years of experience with B2B and B2C products.

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