REJECT-ON-SMTP-DATA (Re: Mail Server best practices - was: Pandora's Box of new TLDs)

Phil Vandry vandry at TZoNE.ORG
Fri Jul 4 16:01:39 CDT 2008


On Tue, Jul 01, 2008 at 11:54:46AM +0200, Jeroen Massar wrote:
> The magic keyword: REJECT-ON-SMTP-DATA.
[snip description on how to reject during DATA phase]
> 
> Unfortunately there is also a side-effect, partially, one has to have 
> all inbound servers use this trick, and it might be that they need to be 
> a bit heavier to process and scan all that mail. Then again, you can 

More than that: you also need to have all users in the domain (indeed
all users who share an MX server) agree on the accept/reject policy.
If users are free to use different spam filtering techniques and tune
them to their liking (e.g. someone uses SpamAssassin with a low threshold,
someone else uses it with a high threshold, someone else uses bogofilter
instead) then what do you do with mails that are addresses to more than
one user? You can have some users reject the message during the RCPT
phase and others accept it, but if you've waited until the DATA phase,
it's too late for that.

-Phil




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