-record(mail, {
    from :: {ok, binary()} | {error, nil},
    to :: {ok, binary()} | {error, nil},
    subject :: {ok, binary()} | {error, nil},
    message_id :: {ok, binary()} | {error, nil},
    date :: {ok, birl:time()} | {error, nil},
    body :: {ok, binary()} | {error, nil},
    headers :: {ok, gleam@dict:dict(binary(), binary())} | {error, nil}
}).