Say, you send an email to – firstname.lastname@example.org, Contact@example.com, and CONTACT@EXAMPLE.COM. As you can see, all three of these emails have the same spelling but the first one is all lower case while the other two are a mix of both upper and lower case. So, what happens when you send an email to all three of these? Do they all go in the same mailbox or a different one? Or in other words – are email addresses case sensitive?
Short answer, no. In most cases, Email addresses are not case sensitive. All three of them will arrive in the same mailbox i.e email@example.com.
Long answer, it depends. There are 2 parts to this question – the username before @, and the domain name after it.
Domains name (i.e. @gmail.com or @techwiser.com) are not case sensitive, so example.com is same as EXAMPLE.COM.
Now, we are left with the username part (the one that comes before @). And technically, it’s up to the host or the email providers to decided if they want to keep the username case sensitive or not.
Most big email providers like Gmail, Outlook and even company email address hosted on Google Suite are not case sensitive. Just to avoid any unnecessary confusion. However, in extreme cases, some large companies, implement case sensitivity on their server as some people can often have the same first and last name. But in general, this creates more confusion, than the usability, which is why most standard email providers avoid case sensitivity.
To test this theory, I did a quick experiment.
Since we are already using firstname.lastname@example.org, I tried to create another email account with the first letter in upper case i.e. Contact@techwiser.com. And I instantly got an error on saying the username is not available. I got the same error on Gmail, Apple ID, Outlook, ProtonMail – which according to most online sources accounts for more than 90% of total email by market share.
In short, while it’s technically possible to make the part before @ case sensitive, most popular email servers do not allow that.
It’s safe to assume, your message will be delivered to same email address, irrespective of upper or lower case, as long as the username’s spelling is correct.