ENUM values are sorted according to the order in which the enumeration members were listed in the column specification. (In other words, ENUM values are sorted according to their index numbers.) For example, 'a' sorts before 'b' for ENUM('a', 'b'), but 'b' sorts before 'a' for ENUM('b', 'a').
telnet 127.0.0.1 25
HELO localhost
MAIL FROM: <user@example.org>
RCPT TO: <user@example.com>
DATA
......