Are emails case-sensitive?

Yes and no. Typically, emails are “case insensitive.” This is always true for the domain portion of an email (the bit that follows the @, for example:,

The format of email addresses is formally defined in RFC 5322 (mostly section 3.4.1) and by RFC 5321 . The local part is case sensitive; for example is a different email from This practice is discouraged by RFC 5321. In other words, when you create a new email, keep it all lower-case even though it most likely will not matter as RFC 5321 is looking to make it case insensitive.

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