What is a valid email address format

The cardinal rule of email marketing is sending email drip campaigns to valid email addresses. But what makes emails valid? Let’s dig into how valid email addresses should look.

An email address is a unique identifier for a mailbox used to send and receive messages, known as emails. There are two types of email addresses – personal or corporate. 

Personal emails are email accounts created on different mail servers. The most popular among them are Gmail, Outlook, and Yahoo! Mail.

Corporate emails are email addresses created on the special internet domain previously purchased by the company. Such addresses usually include the business or brand name. 

Typically, corporate emails are assigned to all company employees and departments for direct communication and business purposes. Such email addresses have the person’s name or field at the beginning (e.g., name@company.com, support@company.com, etc.).

Since the 1980s, email addresses follow specific rules standardized by the Internet Engineering Task Force. To make sure the email address is valid, check the following factors:

1. Email structure

Every email address consists of 3 elements: local-part, @ symbol (pronounced as “at”), and domain name. The local-part is placed before the @ symbol, and the domain name is placed after the @ symbol. For example, in the email johndoe@company.com, “johndoe” is the local-part, and “company.com” is the domain. Emails are invalid without these elements.

The local-part is the username indicating a unique name for the mailbox. 

The @ symbol connects the domain and the person who owns the email address.

The domain name indicates the name of the organization. It’s an address that leads to the organization’s website. 

When an email is sent, the sending mail server checks for another mail server that matches the domain name of the recipient’s address. Let’s say, if someone sends a message to a user at company.com, the mail server first checks if there is a mail server responding at company.com. If so, it will contact the mail server to see if the username is valid. If the user is real, the email will be delivered.

2. Local-part syntax

The local-part or username may be up to 64 characters long and contain:

  • uppercase and lowercase Latin letters (A-Z, a-z);
  • numeric values (from 0 to 9);
  • special characters, such as # ! % $ ‘ & + * – / = ? ^ _`. { | } ~

Note: The period character (.) is valid for the local-part unless it is placed at the beginning or end of an email address. There also can’t be two or more periods in a row (e.g., John..Doe@company.com is not allowed).

The most frequently used special characters are the period (.), underscore (_), hyphen (-), and plus sign (+).  

The local-part can include first name and last name (e.g., John.Doe@company.com) or first initial and last name (e.g. J.Doe@company.com). Names can be capitalized or not capitalized. Both variants mean the same email address. For instance, if the email address is John.Doe@company.com and you are sending an email to john.doe@company.com, the message will still be delivered to John’s mailbox. 

3. Domain name syntax

A domain name consists of one or more parts separated by a dot, such as example.com. Each part must be no longer than 63 characters and can contain:

  • uppercase and lowercase Latin letters (A-Z, a-z);
  • numeric values (from 0 to 9), on condition that domains can’t be all numeric;
  • a hyphen (-), on condition that it is not placed at the beginning or end of the domain.

How to verify an email address syntax?

Invalid emails can make your email campaign ineffective and harm your email account.  

Luckily, there are services that can help with a time-consuming email address check and save your marketing campaigns. Snov.io Email Verifier will make sure your email addresses follow the standard email format rules and clean your list from invalid emails, which will improve the reputation of your email account.

Learn how to validate your email addresses with Snov.io.

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