need help blocking emails to non-existent users

[Alex Broens]

On 12/19/2007 11:33 PM, Julian Field wrote:
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>  From the archives....
> 
> If you are using Exchange 2003 (or 2007 and have installed the relevant 
> edge role on your 2007 mailbox server and have enabled the valid 
> recipient checking, which is all documented in technet), then I would 
> advise using milter-ahead instead of querying the list of valid 
> addresses directly, as it's far more reliable.
> 
> On Exchange 2003, there is a simple tick-box somewhere (Steve at FSL 
> might be able to help you there) which enables SMTP-time rejection of 
> invalid recipients.
> On Exchange 2007, you need to install the anti-spam agents on your hub 
> transport server
> http://exchangepedia.com/blog/2006/09/how-to-install-anti-spam-agents-on-hub.html
> and then enable the invalid-recipient checks by doing
> Set-RecipientFilterConfig -RecipientValidationEnabled:$true
> in the Exchange Management Shell.
> 
> Then use milter-ahead if you are using sendmail or Postfix, available from
> http://www.milter.info/sendmail/milter-ahead/
> It will cost you € 90 euros for a site licence for it, but it's well 
> worth the small investment.
> 
> This is a far more robust solution than trying to reliably read, parse 
> and process all the Active Directory entries, which may be out of date 
> on newly-created accounts, and require far more long-term maintenance 
> than my solution above, which you can just setup and leave alone.
> 

... may want to add that milter-ahead's next release will support 
sendmail's mailertable and postfix's transport maps as a drop in for 
milter-ahead's call-ahead-db

I'm testing the postfix transport maps and it rocks!!!

h2h

Alex