Is Email Case Sensitive????

We all know that email addresses consist of three things:
1) email ID,
2) the @ symbol,
3) a domain.

Many of us think that email addresses are case sensitive and will therefore utilize upper and lower case as in the email address. Frank.Zappa@wildmusic.com

But are emails case sensitive?

The short answer: NO.

The long answer:

Email DOMAINS are explicitly and always case insensitive. The address johnny@website.com is exactly equivalent to johnny@WebSITE.com.

Email IDs are allowed to be case sensitive. However, in practice email IDs are usually case insensitive also.

It is rare that an Internet Service Provider (ISP) distinguishes between upper- and lower-case letters in the email ID.

As a standard rule of practice, email addresses should be presented as lower case.

You can mix the case if you like BUT be careful. If your email system is case sensitive for usernames, you'll need to take that into consideration.

Many companies utilize the mixed case email formats. There is an added usability feature in this option - it helps to separate firstnamelastname email formats:
BobDylan@folkrocker.com

When using separators like dots, hyphens or underscores, there would be no need for mixed case, all lower case is suggested:
elvis.presley@popstars.com
elvis_presley@popstars.com
elvis-presley@popstars.com