Filter/Bbcode.php
protected function _parseBbcodeEmail(&$text)
    {
        $this->_replaceLoop(
            '#\[email\]([^\[]*?)\[/email\]#si',
            function ($matches) {
                return $this->_encodeEmail($matches[1]);
            },
            $text
        );

        $this->_replaceLoop(
            '#\[email=([^\[]*?)\](.*?)\[/email\]#si',
            function ($matches) {
                return $this->_encodeEmail($matches[1], $matches[2]);
            },
            $text
        );
    }
protected function _parseBbcodeEmail(&$text)
    {
        $this->_replaceLoop(
            '#\[email\]([^\[]*?)\[/email\]#si',
            function ($matches) {
                return $this->_encodeEmail($matches[1]);
            },
            $text
        );

        $this->_replaceLoop(
            '#\[email=([^\[]*?)\](.*?)\[/email\]#si',
            function ($matches) {
                return $this->_encodeEmail($matches[1], $matches[2]);
            },
            $text
        );
    }
[email]email[/email] & [email=email]email txt[/email]