let droplist = ["mx.EXAMple.com", "mx2.example.COM"]
let normal_droplist = map normalize_string droplist
let actual = dropby_mxlist normal_droplist mx_map fwds
let droplist = ["mx.EXAMple.com", "mx2.example.COM"]
let normal_droplist = map normalize_string droplist
let actual = dropby_mxlist normal_droplist mx_map fwds