[Greylist-users] Rejecting Mail to unknown users WAS: Got it working! Now a few more questions

[Dennis Wynne]

I finally got the mail rejection to non-users working. It was quite a chore.

My first thought was to add entries in the access file like this:

To:gooduser1 at domain.com RELAY
To:gooduser2 at domain.com RELAY
To:@domain.com REJECT

but that does not work. Sendmail does not check the USER part until after it 
has checked the DOMAIN part - so it was rejecting all the messages.


Then I tried the virtual users table:

gooduser1 at domain.com	gooduser1 at domain.com
gooduser2 at domain.com	gooduser2 at domain.com
@domain.com			error:5.7.0:550 Address invalid

That sort of worked, sendmail would show the error in maillog but would 
still pass the mail onto the greylist Milter.  I saw some things about 
adding the domains to the a virtual domain file, but that is supposed to 
bypass other checks (like RBLs). I found a snippet only to use this in the 
sendmail.mc file

LOCAL_CONFIG
F{VirtHost}/etc/mail/virtuser.domains

and put the domains (e.g. domain.com) in the text file virtuser.domains.

This worked, and it started blocking names not in the virtuserstable - the 
trouble is that mail sent to users in the table errorer out with a recursion 
error. Since the LHS and RHS have the same content, it looped for 50 times 
then errored out.

I found another snippet to add these lines to the sendmail.mc file:


define(`_VIRTUSER_STOP_ONE_LEVEL_RECURSION_', `true')dnl
define(`_NEED_MACRO_MAP_',`1')dnl


and that fixed it.

So if you have a finite number of users, you can list them all in the 
virtuserstable pointing to themselves, add an entry with @domain.com and an 
error messages, and have the system accept only the good users and bounce 
the bad ones - all before greylist kicks in.

I have still trying to get RBLs working. Once I do, the "anti-SPAM" server 
will be ready to go.  I cranked the log level up in sendmail and it does not 
seem that the RBLs are being checked at all.

Dennis



===== Original Message from greylist-users at lists.puremagic.com (Greylisting 
Users and Developers Discuss) at 2/09/06 9:46 am
>Got the relaydelay script working last night. There were several un-obvious
>(to someone who does not work in LINUX all the time) that had to be done.
>
>
>Anyway, a few more questions.
>
>We only have a small number of users, so on our current mail server have
>all
>the "to" names white-listed and "everything else" blacklisted. This takes a
>huge load off the server when there is a new worm going around that tried
>to
>spread by sending e-mail to somename at yourdomain.com ("bob at domain.com" and
>"fred at domain.com" etc).
>
>I need to add this to my greylist box, ahead of the relaydelay script - I
>would assume.  No need to add a triplet to the MySQL database that contains
>a "to name" that will never be accepted by the real mail server.
>
>Is there an easy way to do this?  Keep in mind this server works for
>several
>domain names - so I would like to list the real users like
>"steve at domain1.com" and "david at domain2.com" as valid, and exclude every
>other name - even "steve at domain2.com" if I can.
>
>
>
>
>I use online blacklists with our current mail server - and it does catch
>quite a few messages (not as many as it used to).  What is an easy way to
>add the online blacklist looking to my new server?
>
>I would think it would work best if I could do this, in this order:
>
>1) Make sure the to: of the message is to a real user on one of the domains
>2) Make sure the from IP / from / mail server is not on one of the online
>blacklists
>3) Then hit the relaydelay script to wait to see if the sending server will
>retry
>
>
>Does this sound correct?
>
>I am using CentOS 4.2 w/sendmail sendmail-8.13.1-2
>
>Thanks in advance for any help,
>Dennis
>
>
>
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