PHP 5.3 – ereg() deprecated

If your server is running PHP 5.3+, you’ll get a deprecation notice when ereg() is called on line 351 of wp_mail_smtp.php. This can be fixed by replacing the regex email check with PHP’s built-in filter_var() function for checking emails:

// replace the following on lines 351-353
if (preg_match('^[-!#$%&\'*+\\./0-9=?A-Z^_a-z{|}~]+'.'@'.
        '[-!#$%&\'*+\\/0-9=?A-Z^_a-z{|}~]+\.'.
        '[-!#$%&\'*+\\./0-9=?A-Z^_a-z{|}~]+$', $email))

// change to:
if (filter_var($email, FILTER_VALIDATE_EMAIL))

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