php code:

$structure = imap_fetchstructure($stream, $msg_number);
print_r($structure);
die();

POP3 connection to mail server:
stdClass Object
(
    [type] => 0
    [encoding] => 0
    [ifsubtype] => 1
    [subtype] => PLAIN
    [ifdescription] => 0
    [ifid] => 0
    [lines] => 12
    [bytes] => 860
    [ifdisposition] => 0
    [ifdparameters] => 0
    [ifparameters] => 1
    [parameters] => Array
        (
            [0] => stdClass Object
                (
                    [attribute] => CHARSET
                    [value] => US-ASCII
                )

        )

)


IMAP connection to mailserver:
stdClass Object
(
    [type] => 0
    [encoding] => 3
    [ifsubtype] => 1
    [subtype] => PLAIN
    [ifdescription] => 0
    [ifid] => 0
    [lines] => 12
    [bytes] => 860
    [ifdisposition] => 0
    [ifdparameters] => 0
    [ifparameters] => 0
    [parameters] => stdClass Object
        (
        )

)