[Mimedefang] Nolisting

[WBrown at e1b.org]

Volume 50 of jgc's spam and antispam newsletter had a link for Nolisting, 
Poor Man's Greylisting at 
http://www.joreybump.com/code/howto/nolisting.html .

Basically, the premise is set an MX with a high preference pointing to a 
system that does not listen on port 25.  Broken mailers would attempt to 
connect to it, fail, and not try a lower preference mail exchanger.  A 
real mailer would fall back to a lower pref MX.

When I was first starting with spam filtering, I had 2 server with unequal 
preferences and it seemed that more garbage would head to the lower 
preference exchanger, possibly thinking ti was an offsite backup MX that 
wouldn't have as stringent a filter, or none at all.

What you would end up with is three classes of MX records:

1. One High priority record which point to an address tha doesn't answer 
on SMTP.
2. Medium priority records that point to real mail servers that acccept 
your mail.
3. One or more low priority records that point to addresses that do not 
answer on SMTP.

What does the collective wisdom of the list think about Nolisting, and the 
idea of a low preference MX record as well?

---
The Vista Content Protection specification could very well constitute the 
longest suicide note in history  -- Peter Gutmann 
http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.html

William Brown
Web Development & Messaging Services
Technology Services, WNYRIC, Erie 1 BOCES
(716)821-7285