[Mailman-Users] Filtering Chinese spam.

Kenneth G. Gordon kgordon2006 at frontier.com
Sun Apr 22 21:20:51 EDT 2018

Thank you very much for the information below, Mr. Turnbull. Your last line pretty much 
says it all. I have much to learn yet, and what I am doing now, with the corrections I have 
received here, will serve in the meantime.

Kenneth Gordon

On 23 Apr 2018 at 0:54, Stephen J. Turnbull wrote:

> Kenneth G. Gordon writes:
>  > One of my mailman mailing lists has been suddenly afflicted with
>  > tons of Chinese spam.
> If you have access to the firewall in your mail system, or are
> friendly with its admin, the most efficient way to handle this is in
> the firewall by dropping all traffic from China, as described in a
> thread about "Brute force attacks" starting about a week ago on this
> list.  That is fairly risky these days; you never know when one of
> your members is going to visit China and send mail from a friend's
> address.  As Robert Heller suggests, the next most efficient thing is
> to drop all traffic from China in the MTA (mail server software) using
> similar techniques.
> More to my taste than either would be to install a programmable spam-
> checker like SpamAssassin or SpamBayes, and bump the cost of rules
> that catch Chinese spam if necessary.  This is far more effective and
> efficient than doing it in Mailman, and if your system has mailboxes
> other than those for Mailman, they will also be protected.
>  > I have modified my settings in Privacy Options/Spam Filters thusly:
>  > 
>  > ^Subject: =?utf-8?B?
>  > ^Subject:.*\?{4,}
> As Mark points out, the first is not going to work.  You need to
> "escape" the question marks as in the second expression:
>     ^Subject: =\?utf-8\?B\?
> Both of these filters are risky.  The first is likely to catch any
> email whose subject starts with an emoji, smart quotes, or any other
> exotic characters such as math symbols or a complex smiley (such as
> table flipping or the 7-character shrug).  The second will catch any
> mail with a subject containing 4 or more question marks in a row.  Of
> course these may be desirable if you're running a mailing list for
> junior highschool students ;-), but such subjects are reasonably
> common among educated adults as well in my experience.  How large that
> risk is, and whether or not to take it, is up to you and your
> subscribers, of course.
> Finally, a viable strategy would be to use these filters for now and
> explore the more capable methods at your leisure.
> Regards,
> Steve

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