Milter-greylist

Matt Kettler wrote:
 > manu@... wrote:
 > > Oliver Fromme wrote:
 > > 
 > > > Can milter-greylist be interfaced with hashcash?  (*)
 > > > I would like to whitelist (i.e. not delay) mails that
 > > > contain a valid hashcash header line.
 > > 
 > > That could only fit in a DATA stage ACL, so you will not be able to
 > > avoid greylisting decided at RCPT stage. 
 > > 
 > 
 > It's things like this that make you wish SMTP had a "HEADER" phase.. but it 
 > doesn't, and there's nothing that can be done now to change that. Oh well, 
 > hindsight on protocol design is always 20/20, right?
 > 
 > As a further clarification to Oliver, when it comes to greylisting you're pretty 
 > much limited to information that can be obtained from 4 sources: the connection 
 > itself (ie: source IP address), and the following commands: HELO, RCPT TO: and 
 > MAIL FROM:, and various DNS lookups or other operations based on the data 
 > obtained from those 4 sources.
 > 
 > Any other aspect of the message all comes as one big lump in the DATA phase,

I'm already aware of all of that.

But isn't it possible that -- in theory -- the client side
closes the connection as soon as the headers are received
during the data phase?  A compliant mail server has to
treat that like a 4xx temporary error.  So you would have
to receive all the headers, but not the mail bodies.
Actually I thought that milter-greylist already supported
something like that.

Best regards
   Oliver

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