[Mimedefang] Powerful anti-spam rule :-)

[Dirk Mueller]

On Son, 10 Nov 2002, David F. Skoll wrote:

> This does not work, because Yahoo returns "250 recipient ok" no matter
> what address you put, as long as it ends in "@yahoo.com".  Try it.
> Yahoo does this to avoid dictionary attacks by spammers on Yahoo
> customers. :-)

True, it returns the error after the message body was sent :-(
this used to be different before. weird. I think many mailers don't deliver 
empty messages, so sending a message with an empty body should work here 
too. 

Anyway, this rule still works with many other mailers. many spammers don't 
waste their time on finding valid sender addresses, they just autogenerate 
some random local parts of a given domain (and being admin of one of those 
domains where thousands of bounces with forged sender addresses arrive I can 
confirm that its a very annoying problem). 

This rule is also deployed on many major sites, like e.g. but not limited to 
lists.sourceforge.net.



-- 
Dirk (received 130 mails today)