Re: Sending Non Delivery Reports? (was Pump and Dump)

Garen Erdoisa wrote:
> 
> Well I can only speak for myself, but I have been using SPF now for over 
> a year and have yet to see a case where rejecting an email that failed 
> an SPF check caused any problems. For me at least it solved far more 
> problems that it might potentially have caused.

If the postmaster where I pick up my e-mail from implements SPF to 
reject alleged forwarding, I would lose a significant portion of my e-mail.

One of my public e-mail addresses is a forwarding service, and SPF 
specifically breaks such forwarding services because they all they add 
is a header line, and do not rewrite the other parts of the header.

The "solution" described by the SPF is to require replacement of the 
software in use by the mail forwarding service.

I have seen posted several times on the DSBL and other mailing list 
archives that the RFCs require all systems connected to the public 
internet to have a working rDNS.

Considering that a strict rDNS check foils more spam attempts than SPF 
does, and can not be implemented because there are a few popular 
networks that can not take the 15 minutes to correct their rDNS, an 
anti-spam system that requires a modification or replacement to RFC 
compliant mail processing systems owned by others is not a good solution.

If you run a small domain where you personally know all the users and 
where they get their e-mail from, you can safely implement SPF to reject 
spam/backscatter.

For the large domains that are proposing/promoting it, they do not seem 
to care how many of their users that they are breaking e-mail reception for.

Now as far as your backscatter problem:

Can you modify your DNS server to respond differently to the I.P. 
addresses of the few mail servers generating the backscatter?

If so, present them with an MX record resolving to 127.0.0.1, it will 
eventually eliminate the backscatter from those servers.

-John
[email protected]
Personal Opinion Only