How to Check if the Email Address Format Is Valid

Email marketing has a significant return on investment (ROI), and it plays a crucial role in guiding prospects through your sales pipeline. However, the effectiveness of your email marketing efforts can be significantly hampered by invalid email addresses, leading to hard bounces. This article will guide you on how to check if an email address format is valid.

Understanding the Right Email Address Format

An email address is composed of three parts:

  1. The prefix or username that appears to the left of the @ symbol.
  1. The @ symbol.
  1. The domain that appears to the right of the @ symbol.

The prefix, also known as the username or local-part, can have up to 64 characters and can consist of any combination of numbers, upper and lowercase letters, or some other special characters. Periods are allowed in the prefix as long as they’re not the first or last characters. Also, when using periods in an email address, you can’t use two of them in a row.

The domain to the right of the @ symbol has to match the requirements for a hostname (the name of a computer connected to a network). Each part should have no more than 63 characters and can contain uppercase and lowercase letters, numeric values, and hyphens. However, all numeric domains are not allowed, and hyphens can’t be at the beginning or end of the domain.

Why Validate Email Addresses?

Checking the email address format ensures accuracy before sending the email, leading to improved engagement and conversion rates. It also helps eliminate hard bounces and reduce spam complaints.

How to Verify Email Addresses

There are several ways to verify email addresses:

  1. Check the Email Address Format and Syntax: Ensure that the email address format complies with the rules. However, this doesn't guarantee that the email address is valid.
  1. Use Google: Google can be a useful tool for verifying email addresses, especially for B2B contacts.
  1. Use an Email Finder Tool: Tools like free Linkedin Email Finder from Mailmo can help you verify email addresses. They offer options to manually find or verify the email address and verify or source leads’ email addresses in bulk.


What is the correct format of an email address? Every valid email address should have three components – a prefix or username, an @ sign, and a domain.

Are email addresses case-sensitive? No, email addresses are not case-sensitive.

How do you find out if an email address is invalid? There are a few things you can do to check if an email address is invalid:

Remember, before you fire off that email, make sure there’s a recipient on the other end. Check the syntax and use the right tool to verify email addresses without sacrificing your deliverability.