The significance of character case within an email address’s structure is a common point of inquiry. Specifically, the question often arises whether utilizing uppercase letters instead of, or in conjunction with, lowercase letters affects the delivery or interpretation of electronic mail. For example, would “Example@Domain.com” be treated differently than “example@domain.com”?
Historically, the underlying protocols governing email transmission are designed to treat the local part (the portion before the “@” symbol) as case-sensitive, theoretically allowing for distinct mailboxes differentiated solely by capitalization. However, in practice, most modern email systems and servers disregard character case in the local part. This widespread implementation of case-insensitivity prevents accidental misdirection of email and streamlines user experience. Domain names (the portion after the “@”) are explicitly defined as case-insensitive.
