Yakov Shafranovich wrote:
[Subject changed to be more readable, was "Re: [Asrg] [1] Why SPAM is worse in SMTP than in other protocols". Mod.]
Alan DeKok wrote:
I've written a *very* rough first draft of a document. It's available at: http://www.striker.ottawa.on.ca/~aland/smtp-sucks/problems.txt
Some comments:
Isn't SMTP an MTA-to-MTA protocol, with SUBMIT being the "submitter to MTA" protocol?3. The sender can request that the message be forwarded to (almost) anyone else. SMTP isn't a "user to user" protocol. It's a "submitter to MTA" protocol. In the case of open proxies, the MTA may be abused to re-send the mail to anyone on the net.
This also has to do with the fact that the body of the message and the SMTP transaction are separate from each other.6. no negative feedback TCP has congestion control. ICMP "port unreachable", etc. When SMTP messages are thrown away, they're often done so by the end user. The recipient MTA usually doesn't know, and the originating MTA doesn't know. So in the absence of negative feedback, spammers increase their sending rates, in the hope that some messages will get through.
What to do about it -------------------
A good example would be giving a higher value to unknown senders in SpamAssasin.e.g. Messages from unknown senders should be treated with great suspicion. Any and all available information should be used to determine how to process the message.