mailheader: convert to ES6 (#2213)
mailheader: convert to ES6 (#2213)


haraka/Haraka,msimerson/Haraka,msimerson/Haraka,smfreegard/Haraka,haraka/Haraka,smfreegard/Haraka,msimerson/Haraka,haraka/Haraka,smfreegard/Haraka,smfreegard/Haraka,msimerson/Haraka,haraka/Haraka