In early email systems, several email formats were tried. Only one survived, though, and that's the familiar username@entity.TLD (with TLD being the top-level domain such as .com, .org, .net, and .gov) format used today. The maximum length of an email address based on this format is 254 characters, although that wasn't always the case.

Character Limitations in an Email Address

Every email address consists of two parts. The username comes before the @ sign, and the domain name follows it. In "person@company.com," the username is "person" and the domain name is "company.com."

The total length of an email address in the original standard was 320 characters. The standard limited the username to 64 characters and the domain name to 255 characters. (If you're doing the math, that adds up to 319. The final character is the @ symbol in between.)

This 320-character limit is different from the 254 figure because the current standard limits the total length of an email address to 256 characters, including punctuation. Some addresses, however, use angle brackets (<>), which take up two characters, leaving the maximum number of characters used in an email address at 254.

So, when creating a new email address, limit your username to 64 or fewer characters, and the total number of characters to 254. Just remember that the shorter the email address is, the easier it is for people to remember.