Matt Kettler mkettler at evi-inc.com
Tue Mar 25 22:03:25 GMT 2008

--[ UxBoD ]-- wrote:
> Hi,
> Is anybody using TMDA with Postfix, especially the challenge/response element of it?  Thoughts?
> Regards,

Beyond the fact that it irritates people (ie: every time you get spammed, you 
wind up sending unsolicited challenges to some innocent third party.. In effect, 
they get spammed every time you do), there are other problems with TMDA.

Fundamentally, TMDA boils down to a system of outsourcing your spam filtering 
onto others, irritating them by doing so without their consent, and then hoping 
they'll behave the way you want and handle it for you.

TMDA breaks down when it encounters people like me.

Whenever I get a challenge for a message I did send, I consider who benefits 
from the message. If the delivery of the message benefits the recipient more 
than me, i.e.: I'm giving away advice for free, I delete the challenge without 
approving it. I've already expended enough work writing a response to their 
question. I'm not going to jump through extra hoops after the fact to deliver it 
to them.

Whenever I get a challenge for a message I don't believe I sent, I immediately 
approve it. After all, I don't want to be responsible for them missing out on an 
email when I'm unsure of the content, it could be important to them...

In both cases, their system just sent me an unsolicited message. Now that 
they've ticked me off by spamming me, why should I cooperate? As far as I know, 
nobody has offered to pay me, or even politely asked me to handle their spam 
filtering. Why should I reward them for such impolite behavior? What would you 
do if your neighbor took a leaf blower and blew all his leaves into your yard 
without asking? would you bag them for him? I wouldn't. I'd use my leaf blower 
to blow them back where they came from.

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