Uk postcode regex producing false possitives

I'm trying to pick out post codes from an array. I am using the post office's regex to find the matches.

$postcodeRegex = "/(GIR 0AA)|((([A-Z-[QVX]][0-9][0-9]?)|(([A-Z-[QVX]][A-Z-[IJZ]][0-9][0-9]?)|(([A-Z-[QVX]][0-9][A-HJKSTUW])|([A-Z-[QVX]][A-Z-[IJZ]][0-9][ABEHMNPRVWXY])))) [0-9][A-Z-[CIKMOV]]{2})/";

foreach( $content as $key => $line ){
    if( preg_match($postcodeRegex, $line, $matches) !== false ) {
        $points[] = $key;
    }
}

But preg_match keeps is producing false positives. For example the line below is shown as a match.

HYPERLINK "mailto:email@address.com" email@address.com

My regex skills are very poor. How do i cut down on these false positives?

thanks