Are email addresses case sensitive?

Having invalid email addresses on your list can cause bounces and prevent email from reaching your leads. Incorrect syntax causes many validity failures, and often comes up as a source of confusion for email marketers. In this article we address a common grey area: uppercase letters and, in general, are email addresses case sensitive?

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Are email addresses case sensitive?

Are email addresses case sensitive?

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The short answer is technically yes. However, typically email addresses are not case sensitive: if you type your email address into a form and accidentally capitalize a letter or two, it probably won’t jeopardize the sender’s ability to email you.

We must explore the issue in more depth to get a clear answer: to shed some light, let’s first look at basic email address structure, and then discover the different rules between the local part and the domain part.

What are the different parts of an email address?

An email address is composed of two main parts:

local part – the part before the @ symbol

domain part – the part after the @ symbol

When it comes to case sensitivity, the rules differ between each part.

Are email addresses case sensitive?

Is the domain part case sensitive?

No, in accordance with RFC 1035, the domain part of the email address is case insensitive.That means you could type in:

[email protected]


[email protected]

and both would return the same results. Similarly, regardless of the email service provider, if a user capitalizes a letter by mistake in your entry form, it’s still considered valid.

Keep on reading to know if are email addresses case sensitive.

Is the local part case sensitive?

Yes, according to RFC 5321, the local part is case sensitive. However, Email Service Providers (ESPs) widely recognize that allowing upper case letters can lead to unnecessary confusion. That’s why most ESPs limit the options available to users when creating an email address.

Which leaves you questioning if are email addresses case sensitive.

Basically, while ESPs technically can give their users that flexibility, they typically choose to not to, in an effort to maintain consistency and standardization.That means:

[email protected]

may return different results from

[email protected]

depending on the email service provider. But in most cases, both would reach the same recipient.

Keep on reading to know if are email addresses case sensitive.

How can I learn more about email address syntax?

At Verifalia we’ve covered some common syntax issues in depth in our knowledge base, so check out these articles: [insert links to other syntax-related articles].

Just remember: while it can’t hurt to familiarize yourself with basic syntax standards, consider these articles a trusty reference. You’ll save yourself plenty of time and headaches by verifying syntax with Verifalia, rather than trying to check each address manually.

Invalid syntax can cause emails to bounce, but as an email marketer you may face a variety of other validity issues that can affect your deliverability. Check out our knowledge base articles to learn about more complex issues, like greylisting and SMTP tarpitting.

Keep on reading to know if are email addresses case sensitive.

Can You Use Special Characters in an Email Address?

A special character cannot appear consecutively two or more times in an email address. It also cannot be the first or last character.The period (.) is the special character that is used the most frequently.the underscore (_), the hyphen (-), and the plus sign.

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Special Symbols

When creating your email address, you have the option to use special characters that make your email address unique. Different requirements may be enforced by different providers.

Email servers generally recognize the following characters as unique characters. When using language, it is important to be aware of the impact that it has on other people.

Words can have a positive or negative effect on the way people think and feel, and it is important to use language responsibly. It is important to be careful when using language because it can have a powerful impact on people.

Words can have a positive or negative effect on the way people think and feel, and it is important to use language responsibly. 

You may not be aware, but Gmail allows you to use special characters in your email address. What could be the possible reasons for this discrepancy? Yes, that is an accurate statement. You are correct in your assumption. 

Gmail does not allow any of the special characters listed above. Gmail doesn’t allow the symbols – and +. In email addresses, only letters and numbers are allowed.

Not commas, not parentheses, and not brackets. Using unique addresses can make you stand out from general addresses, but resist the temptation to use special characters.

Keep on reading to know if are email addresses case sensitive.

Are the rules for creating and managing outlook contacts case-sensitive?

 If the email address is correct, it doesn’t matter if the address is in upper or lower case. Some email servers struggle to correctly recognize upper-case letters.

I recommend using the same address to avoid bouncebacks. Outlook rules are not sensitive to case. When you are writing a paper, you should always keep in mind the following guidelines.

Do Gmail addresses have to be in all caps? 

Gmail addresses are not case-sensitive.

Are capitals important in Gmail email addresses?

Lowercase and uppercase letters behave the same in Internet email. Computer servers do not distinguish between upper and lower case. For example, [email protected] and [email protected] and [email protected] are the same for servers.

Does the case count? Especially not

is [email protected] the same as [email protected] in terms of mail servers?

The domain name in an email address is not case sensitive; H does not matter whether you use uppercase or lowercase letters. The same goes for usernames, although outdated mail servers can, in rare cases, misinterpret cases. For simplicity, it’s best to use only lowercase letters in a username.

Helps avoid email address confusion

To minimize the risk of email delivery errors in your email address:

When creating a new email address, use only lowercase letters.

If possible, avoid unusual or fancy spellings. You run the risk of your contacts forgetting your address if your name is Susan Davis but your email address is [email protected]

To conclude, does capitalization matter in email addresses?

Short response: No!

An email address can begin with a capital letter or contain capital letters anywhere. Don’t worry if your email address is capitalized or your autocorrect just doesn’t work.

You’ll be fine!

Email addresses are case-insensitive, in contrast to passwords.

Your email server will read it the same way regardless of whether you use capital letters or not, as long as the numbers and letters match your official email address. 

In this article, we answered the question of are email addresses case sensitive.

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