When creating an email address, you can use either lower or upper case letters. Most people use lower case because it is easier to type, but there is no wrong way. If you create an email address, You must include your domain name in the email (e.g., @example.com). Even though you can write the local part of the email either in Upper or Lower format, the domain part can only be in lower case.
Short answer: No, it's not a requirement for your email id to always be lowercase.
The first and most crucial step in creating an email address is to ensure that the format of the email address is correct. We need to validate it against some regular expression rules to do this.
The format of an email address is simple. It consists of two parts: domain and local part. The domain part is the one that appears after the "@" character. The local part is the part that's present before the domain part.
Furthermore, we can refer to an RFC (Request for Comments), which specifies the rules to be followed when creating email addresses.
The formal definitions are in RFC 5322 (sections 3.2. 3 and 3.4. 1) and RFC 5321—with a more readable form given in the informational RFC 3696 and the associated errata.
When you receive an email, the first thing you see is the sender's address. The email address has several different parts, each with a specific purpose. The domain name is always in lower case, while the user name is in upper case. The domain name is the part of the email address that identifies the sender's internet service provider (ISP). The user name is the part of the email address that identifies the recipient.
RFC 4343 defines that domain names should always be case insensitive and, hence, always in lower case. On the other hand, the user name can be in either upper or lower case. Still, it is usually best to use lower case letters when creating an email address. This makes it easier for people to identify to whom the email belongs and easier to type.
In general, you should use lower case email addresses. However, there are some exceptions. For example, suppose you are sending an email to a company or organization. In that case, you may want to use the upper case for the company or organization's name.
It's interesting to note that the name of a company or organization can be the same case as its email address. For example, ABC Company might use [email protected], and XYZ Company might use [email protected]
Though these Upper and Lower case combinations look fancy and catch attention, the emails are case-insensitive according to RFC standards. So, even [email protected] is also considered to be the same as [email protected]
In conclusion, it is up to you to use lower or upper case for your email address. Whichever you choose, be consistent with it throughout your emails. Also, include other contact information, such as your phone number and website, if someone needs to contact you urgently. Thanks for reading!