sendmail-8.12.6+cyrus-imapd-2.0.17: check presence of the cyrus mailbox during establishing SMTP connection

Mike Brodbelt m.brodbelt at
Tue Nov 4 20:57:01 EST 2003

> On Tue, Nov 04, 2003 at 06:35:31PM +0100, Andrzej Filip wrote:
>> Mike Brodbelt wrote:
>> There are two alternative approaches I can think of right now:
>> 1) custom milter
>> [servicing only "RCPT TO:"]
>> 2) socket map
>> [ available in 8.13 preview
>> ]
> It seems to me that the proper place to achieve this integration is
> during the SMTP authentication process.  If all IMAP users should be
> allowed to use SMTP, then it's easy to do by checking the IMAP
> authentication database.  If only certain IMAP users should be allowed
> to use SMTP, it becomes a bit more complicated.  A good way to isolate
> all of the authentication and authorization is to do it with PAM
> modules.

FWIW, my interest in it isn't for authentication, but rather as spam
control. At the moment, we get a lot of junk addressed to bogus users in
our domain. This is accepted by sendmail, which then tries to deliver it
to Cyrus. Delivery fails with a no such user error, and a bouce is
generated, which invariably goes nowhere, as the spam had a forged from
address. I'd like to be able to send 550 messages back in the initial SMTP
session when the local user doesn't exist, but I don't want to switch
sendmail into interactive mode for all deliveries.
ATM, the only way to achieve this involves breaking Cyrus' "black box"
model. I'm very interested in anything that can present a solution to

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