Should env_To checksums work with greylisting?

Vernon Schryver vjs@calcite.rhyolite.com
Mon Dec 8 03:10:04 UTC 2003


> From: Gary Mills <mills@cc.UManitoba.CA>

> ...
> Yes, that's how I expected it to work.  However, there must be something
> different going on with env_To checksums.  I assume that it has to do
> with multiple recipients, only one of which is whitelisted.  I assume
> that with greylisting, it's the entire message that's given the
> temporary failure response.  The usual trojan spam engine doesn't
> retry, so the mail disappears.  Would this be correct?
> ...

Yes, since the DCC greylisting looks at the message body, if any
target address is not whitelisted for greylisting, then message is
subject to greylisting.

At the end of the SMTP DATA command, an SMTP server can say only
"250 ok", "4yz try later," or "5yz permant failure" to the entire
message.

Checking the entire message is a valuable feature.  It means that
spammers cannot get through the greylist merely by retransmitting
from the same IP address and envelope sender to the same target.
They must also keep the body of the message identical.


Vernon Schryver    vjs@rhyolite.com



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