Spam trap vs. User Unknown

Vernon Schryver
Tue Jan 28 20:25:49 UTC 2003

> From: Daniel V Klein <>

> I have a number of spam-trap addresses, and I also get a lot of "Unknown
> User" emails.  Some of them are legitimate mistakes, many are spam.  I'd
> like to checksum the bad-address mail, but still give a bad-address reply.
> Is this possible?  Somehow, I think it violates the SMTP chat, but I dunno...

SMTP includes only a single chance to say "no, not that target address,"
and it happens before the body of the message is sent.  
An SMTP server must say "yes, that target address is good" before it
sees the body of the message.  After receiving the body of the message,
there is no way for the the server cannot change its mind and say
"that target address was bad."

Thus, a message addressed to only one or more "Unknown" target addresses
might be reported to the DCC and then rejected.  However, a message
sent to both unknown and valid addresses (perhaps including spam traps)
could not.

Vernon Schryver

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