When the directory authorities refuse a bad relay's descriptor,
encourage the relay operator to contact us. Many relay operators
won't notice this line in their logs, but it's a win if even a
few learn why we don't like what their relay was doing.
Resolves ticket 18760.
I didn't specify a contact mechanism (e.g. an email address), because
every time we've done that in the past, a few years later we noticed
that the code was pointing people to an obsolete contact address.
