Are Emails Case Sensitive? Get the Rules of Creating an Email Address

Writing an important email can be stressful. After you finish writing the email you read over it to make sure you didn’t make any mistakes. Maybe you decide to read over it a second time, and even a third. But there’s one part of an email that not many people think about double-checking: the email address. This begs the question, are emails case sensitive?

This question has been thrown around for years. Even everyday computer users still wonder if emails are, in fact, case sensitive. In this article, we’re going to explore this question and finally get to the bottom of it for you.

Parts of an Email Address

If you take a look at your own email address, you’ll see that it can be split into three sections. There’s your email username, the at (@) symbol, and your email host. For example:

In this email, the email username is “emailme,” and the host is “Gmail” (Google’s email service). Typically, when you’re creating an email address, the email provider will allow you to set your username up to 32 (but possibly more) characters long. However, in theory, an email address can be as long as 64 characters.

Your username can include almost any character on your keyboard. This includes regular letters and numbers, but you may also be allowed to add special symbols (!?#%&, etc.). When it comes to the email host domain part of an email address, this can be a lot longer.

A valid email can have the host section as long as 255 characters. Obviously, this isn’t common practice. Popular email providers like,, and Yahoo Mail all barely make it to 10 characters long. But, if you wanted to create your own email host, you can make it fairly lengthy!

Also, get to know more about How to use iCloud mail account on Android as well as Gmail Account Recovery.

Is an Email Address Case Sensitive?

This isn’t as straightforward as we’d like it to be – when asking “are emails case sensitive?”, the answer is yes and no.

If you take the time to review RFC 5321, a computer networking publication, you’ll find that only the email username is case sensitive. Referring back to our example before, wouldn’t be considered as the same email address as To make the ambiguity of this answer, this isn’t always the case.

Email providers are capable of removing this rule if they’d like to. In some ways, it’s beneficial to remove the question of are emails case sensitive. Consider the everyday computer user: when you type an email, do you proofread what you’ve written? Chances are you do. But what you won’t normally proofread is the email address. Even just starting an email address with an uppercase letter would send it to the wrong person. If an email isn’t case sensitive, this isn’t a problem.

You are moving onto the email host part of the email address. According to RFC 1035 (another networking publication), this part of the email address is never case sensitive. It won’t matter if you type it in all uppercase, all lowercase, or even randomly uppercasing letters. As long as you have the correct domain in place, capitalization doesn’t matter.

For example, can be considered the same email address as So, are emails case sensitive? Yes, in certain regards they are in fact case sensitive. You should always assume this when you send an email.

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Email Addresses in Practice

So far we’ve found out that email addresses aren’t completely case sensitive. They are to an extent, but generally speaking, it’s safe to assume email addresses are not case sensitive. The biggest email providers (Gmail, Hotmail/Outlook, Yahoo Mail, etc.) all act under this assumption. Like we said before, this can prevent any confusion if someone accidentally types an uppercase letter.

Our suggestion though is that if you want to be certain that your email provider has the same answer to ‘our emails case sensitive‘, then you should check their own help pages.

Let’s consider the publication we referred to before – RFC 5321. Another point that this document makes is that ideally, we should create email addresses using only lowercase letters. Not only does this prevent general typos from wreaking havoc, but it avoids email delivery issues. The same applies when sending an email – try to use only lowercase letters when entering the recipient’s address.

That said, when you are emailing someone who has a mixture of uppercase and lowercase letters, enter their email address as accurately as you can. Again, this tends to avoid any needless errors or delivery problems. Usually, this isn’t necessary when using a major email provider like those above. But this can put your mind at ease and minimize the chances of your email being sent to the wrong person.

Quick Note About Gmail

Google’s email system is somewhat different from other providers. Settings aside the question of “are emails case sensitive?”, Gmail email addresses aren’t sensitive to dots/periods. What does this mean?
Once again, consider the email address If you were to send an email to the address accidentally, it would still arrive in the recipient’s mailbox.

Are Emails Case Sensitive

This also means that if you wish to register, but someone else has the account for or, you won’t be able to claim this address. Although this seems like a rather peculiar issue, this is likely just another measure to prevent accidentally sending emails to the wrong people.

Rules of Creating an Email Address

When email addresses were originally introduced, there were very basic rules that accompanied them. Emails were only able to include:

  • Letters from the Latin alphabet
  • Numbers (0 – 9)
  • Certain ASCII characters

Over the years these rules have been subject to change. A group known as the Internet Engineering Task Force (IETF) has contributed to various publications, including the RFC documents we’ve noted throughout this article. Some notable publications included:

  • RFC 6530. The original document outlining the regulations of international characters.
  • RFC 6531. An expansion upon the regulations stated in RFC 6530.
  • RFC 6532. The document which resulted in emails being changed from 7-bit to 8-bit ASCII.
  • RFC 6533. An updated document that adjusted previous limitations of email standards.

It goes without saying that there’s a lot more detail within these documents. However, this gives you an idea of how useful they’ve been to the development of email services.

Continuous updates were made to email standards over the years. As such, we’re now able to go outside of basic ASCII. Chinese, Japanese, Greek, and many other languages can be written in an email address now. In the past, this wasn’t possible!

Email providers aren’t required to make their services compatible with international email addresses though. This has led to limitations of using certain providers.

Take Outlook, for example. You can send emails to an international email address without issue. However, you aren’t able to create an international address with them. Gmail works in a similar way.

How to Keep Your Email Address Safe

In this final section, we’re going to take a look at some of the was to keep your email address safe. If you sent an email to the wrong person because of a typo or because your provider’s system is case sensitive, this can result in sensitive information getting into the wrong hands. Here are a few tips:

  • Doublecheck the email address. The obvious thing to do is double-check the recipient’s email address. If you have their address written down or they’ve texted you it, compare the address they’ve given you with the address you’ve typed into the recipient box. It’s easy to make a typo, and this will ensure you send the email to the right place.
  • Never open emails from unknown people. One of the biggest warnings regarding online safety in recent years has been opening unsafe emails. You might think that just opening an email is fine as long as you don’t click any links, but that’s false. Even simply opening the email can infect your computer and compromise your email account!
  • Avoid public computers. Using a public computer is convenient if you don’t have a computer at home. It’s also useful if you have to send an important email quickly. But due to how many people have access to public computers, they’re risky to use. If you have no other choice, then our advice is only to send basic emails – wait until you have safer access to send sensitive information.
  • Install an anti-virus program. Most modern anti-virus protection programs include email protection too. The likes of AVG and Avast both provide an extra layer of security that will warn you if any suspicious emails come your way. You know, nowadays, there are many ways to hack Gmail password. Also, get to know how to delete Emails from iPhone permanently.

To Conclude for “Are Emails Case Sensitive”

To wrap things up, now you know the answer to your question. Are emails case-sensitive? The answer depends on who you register your email address with. For the majority of email providers though, email addresses are not case sensitive. Furthermore, you’ve now found out about the structure of an email address and the changes made to email standards.

If you still aren’t sure about case sensitivity when it comes to email addresses, check your email provider’s website. Since each provider has its own rules to follow, the only way to get a definitive answer is by checking their help pages.