'Extract "mailto:" email addresses
:param tag_name: The tag which is being parsed
:param attrs: The attributes for that tag
:return: Store the emails in self._emails'

def _find_emails(self, tag, tag_name, attrs):

    filter_ref = self._filter_ref
    for (_, mailto_address) in filter(filter_ref, attrs.iteritems()):
        if ('@' in mailto_address):
            if mailto_address.lower().startswith('mailto:'):
                try:
                    email = self._parse_mailto(mailto_address)
                except ValueError:
                    pass
                else:
                    self._emails.add(email)
