Mail addresses are not case sensitive

I recently wrote that cPanel mail account names are case sensitive for purposes of login. This means that if you created a mail account as rover@dog.com, you cannot login as ROVER@dog.com. That login name, because the case differs from how the account was created, is wrong.

E-mail addresses, whether on a cPanel server or anywhere else, are case insensitive. Mail sent to rover@dog.com, Rover@dog.com, and RovEr@DoG.com will all go to the same mailbox, because that’s how e-mail works: case insensitive. Both the user name (the part before the “@” character) and the domain name are case insensitive.

For example: rover@dog.com and Rover@dog.com would resolve to the same address when mail is sent to them, but when logging in rover@dog.com and Rover@dog.com are two different logins.