Length of email address is an industry standard, lady "The format of email addresses is local-part@domain where the local part may be up to 64 characters long and the domain may have a maximum of 255 characters[2]—but the maximum of 256-character length of a forward or reverse path restricts the entire email address to be no more than 254 characters long.[3] 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[4] and the associated errata.