':return:
A unicode string'

def __unicode__(self):

    if (self._unicode is None):
        contents = self._merge_chunks()
        if (contents.find('@') == (-1)):
            self._unicode = contents.decode(u'ascii')
        else:
            (mailbox, hostname) = contents.rsplit('@', 1)
            self._unicode = ((mailbox.decode(u'ascii') + u'@') + hostname.decode(u'idna'))
    return self._unicode
