[Mimedefang] md_check_against_smtp_server and exchange

David F. Skoll dfs at roaringpenguin.com
Thu Jun 7 10:40:39 EDT 2007

Dave Helton wrote:

> Currently, I can telnet to the exchange server and at the RCPT FROM
> with a bogus address I get a code 250.  I have checked everywhere
> I can think of on the exchange server that would allow any address
> for the domains on that box.  The exchange server allows any address
> to be received, but sends a dsn _after_ receipt.

Some versions of Exchange (I believe older than 2003) cannot reject
invalid recipients at RCPT time.  This is totally broken behavior and
the only fix is to upgrade (preferably, away from Exchange altogether.)

2003 and later let you fix the broken behavior.

See http://www.msexchange.org/tutorials/Sender-Recipient-Filtering.html
and look at "Recipient Filtering", especially the
"Filter recipients who are not in the Directory" option.



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