$re = '/((\[\d+:\d+:\d+ \w+\][\w ]+:)|(\[\d+:\d+:\d+ \w+ \| \w+ \d+:\d+:\d+ \w+\][\w ]+:))([ \w\'.,]+)/';
$str = '[9:14:51 AM] Jeff: If you could just do me a favoure and list all these concerns and in a mail and if you have any ideas that you might want to implement so that I can get everybodys notes.
[9:14:56 AM] Timmy: in terms of websites or domains or DNSs I have no clue about setup
[9:15:19 AM | Edited 9:15:25 AM] Jeff: That, I will get Sam and Frodo involved in
[9:16:01 AM] Jeff: I am stepping out quickly';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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