Every time you attempt to parse HTML with regular expressions, the unholy child weeps the blood of virgins, and Russian hackers pwn your webapp. Parsing HTML with regex summons tainted souls into the realm of the living. HTML and regex go together like love, marriage, and ritual infanticide. The cannot hold it is too late. The force of regex and HTML together in the same conceptual space will destroy your mind like

SwiftTransportException in AbstractSmtpTransport.php line 383: Expected response code 250 but got code "530", with message "530 5.7.1 Authentication required "

Finally, and this is the biggest problem IMO : this is magic. And magic is very very bad, because you have to know how the magic works to use it properly.