$re = '/http.*=20$(*SKIP)(*FAIL)|=20/m';
$str = '$correspondence = <<<EOF
Hello=20
=20
Thank you for getting back to me.=20
The link you need is http://domain.com/index.php?id=204726 .=20
Regards=20
EOF;';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php