You are not fooling us with broken bounce addresses

November 23, 2013

This is a close cousin on my previous blog entry on broken bounce addresses, but today I'm feeling less charitable. Right now we have sitting in our mail queues a bounce that's trying to be delivered to the address mailreturn@smtp.ymlp44.net and has been for the past ten hours. From past experience I know that this message will never be delivered; it will sit there until it times out.

Since this is an actual bounce, the original message was not scored as spam (we automatically discard bounces of spam). But this is not fooling anyone about what business 'Your Mailing List Provider' is really in. When you claim to be a legitimate mailing list provider but do not accept bounces back, well, people notice (especially if the envelope sender address looks like something that exists to catch errors and so on). Certainly we do. In fact you are fooling us far less effectively than if you accepted the bounce, complaint, or whatever and silently swallowed it.

(We'd probably never notice that. To do so we'd have to do some sort of analysis of common bounce target addresses or bounce target domains, and that's just not something we'd ordinarily do. The way you catch the eye of most sysadmins is to sit around in something that we pay attention to, such as our mail queues.)

I'd say that I don't know why people do this, but actually I do. It's pretty easy. If you're setting up a bunch of different sending machines and giving them all their own domains and hostnames that they'll use in envelope sender addresses, it's that much more work to have them listen for incoming SMTP (even if they just discard everything). And you certainly don't want to MX all of your sending domains to something common because that could give people who want to block all of your activity an automated way of recognizing you.

Written on 23 November 2013.
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Last modified: Sat Nov 23 02:08:59 2013
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