Rejecting Mail at RCPT

[Pete]

Spicer, Kevin wrote:

>Raymond Dijkxhoorn wrote:
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>>Hi!
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>>>Does anybody know of a way to get Sendmail to check with a remote
>>>SMTP server to see if a user is valid at the RCPT TO:?
>>>At my site, a good portion of the spam we get is to invalid users.
>>>If i can get Sendmail to check with the Remote SMTP server
>>>before it queues it, that would reduce the amount of spam on my site
>>>by at least 30%!
>>>
>>>
>>Put your users in LDAP and check with LDAP on your frontend servers.
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>Does anyone whether its possible to check against Active Directory (it is LDAP after all)?  I tried once and failed - and never had the time to pursue it.  If so, is there a howto anywhere?
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I have a great perl script that will pull all the email addresses from
AD and make an access map for postfix - "user at domain.com   OK" is the
access map format for postfix, should be easy enough to change to
whatever sendmail requires? Far better than doing a query on your AD for
every new mail that arrives, and less prone to failure of delivery
should the AD become unavailable, even if briefly. Will email you
tomorrow if you like - does your AD have MS Exchange info?