Could Case Sensitivity in Email Addresses be Costing You Business?

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Have you ever wondered if email addresses are case sensitive? If your email address is [email protected] and someone enters it all in lowercase will it still be delivered to your inbox? This post will explain how email syntax works and if capitalisation matters.

You might be creating a new professional email or an email for a brand new marketing campaign. You like the look of it, but then you start thinking. Are email addresses case sensitive? Will adding capital letters and various symbols negatively impact deliverability?

Does your email comply with Email Address standards?

Email address standards are a set of rules all email addresses have to follow in order to be valid. All email addresses follow a specific structure.  They consist of a local part (also known as your username), which comes before the @ symbol. This is the ‘johndoe’ part of [email protected]. Followed by the domain name which appears after the @ symbol. ‘’ would be the domain in this case.

As long as your local part and domain name syntax is valid, the email will be delivered. So what are the rules for creating those?

Username Syntax

  • Can be up to 64 characters long
  • May contain uppercase and lowercase Latin letters (A-Z, a-z) 
  • Can contain numeric values (0-9)
  • Special characters are allowed, such as # ! % $ ‘ & + * – / = ? ^ _`. { | } ~
  • A period character (.) cannot be used at the start or end and you can’t have two periods in a row

Domain Name Syntax

  • May contain uppercase and lowercase Latin letters (A-Z, a-z)
  • Numeric values (0-9)
  • Hyphen (-) as long as it’s not at the start or end of the domain name

Are email addresses case sensitive?

The short answer is no. Most major ISPs and Mail providers are case insensitive and should not cause any issues with mail delivery. Customers entering your email address in all lowercase, will still be able to reach your inbox. 

In rare cases, outdated servers or programs may not interpret capitalisations correctly which may lead to problems. Also, some email servers don’t accept certain symbols.

This is why it’s best to follow some of the good practices outlined below.

Good practice for creating an email address

When creating an email address for yourself or your business the goal should be to make it easily recognisable by both internet service providers and your recipients. Additionally, configuring your domain correctly can help improve email deliverability.

Keep it simple

Best advice is to keep it as simple as possible. Just because you can use fancy characters and numbers does not mean you should. By avoiding lots of capitalisations and symbols your email address will be more readable.

Keep it lowercase

You can use capital letters in your email address. However, keeping it all lowercase is best practice. Because you decrease the chance of running into issues or causing confusion.

Limit use of periods (.)

You might want to use a period there to separate your first name and last time if you choose to. Just don’t overdo it with periods. Others can find it tedious to correctly read your email address.


Are email addresses case sensitive? No. Although when creating professional or business emails that are intended for wider audience you are best avoiding capital letters and keeping symbols to a minimum.

Are you a business owner looking to set up a business email? We can help you with that. Globe2 provides clients with professional emails hosted on Microsoft Exchange. Our highly rated support team can help with the setup and maintenance to make sure your business email runs smoothly.

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