Like every other email address, Gmail address is a combination of two parts that are separated by the @ symbol. The part before @ is the username or local-part and the part after @ is the domain name or domain part. Both names may contain both upper-case and lower-case letters numbers, dots or periods, and underscores. Case sensitivity typically means treating lower-case and upper-case letters as distinct letters.
Are email addresses case sensitive?
Quick answer is “No”. Theoretically speaking domain part is case insensitive and the local part is case sensitive. Let us consider the e-mail address “email@example.com”
Domain names are case insensitive implies one can use Domain.com or domain.com or DoMain.com. All mails go to intended user address. As local part of email address is case sensitive, geeksforgeek is different from GeeksforGeeks.
Therefore theoretically firstname.lastname@example.org is different from GeeksforGeeks@domain.com.
If email providers are treating email addresses as case sensitive, it can create a lot of mess and interoperability problems. Hence the majority of the latest email providers either auto-correct case or ignore case. Therefore except for few outdated email servers, email addresses are case insensitive.
What about Gmail addresses?
As Gmail addresses ignore the case in local part they are not case sensitive. For example, Gmail server will treat the following Gmail addresses as same and will be delivered to the same intended user:
Note: Gmail address is not dot sensitive also, which means that the owner of email@example.com will receive the email even if it has been sent to the following Gmail addresses: