Mailing List SIMS@mail.stalker.com Message #15236
From: Christopher Bort <cbort@globalhomes.com>
Subject: Re: Help
Date: Wed, 24 May 2006 15:42:06 -0700
To: SIMS Discussions <SIMS@mail.stalker.com>
X-Mailer: Mailsmith 2.1.5 (Blindsider)
On 05/24/06 at 13:55, lcs@spellnetwork.com wrote:

> Thanks for the reply.
>
> On May 24, 2006, at 4:38 PM, chris wrote:
>
> >> 1.  I want to totally reject any mail that is not addressed to an
> >> account on sims - how do i do that?
> >
> > As long as you don't have an account called "Unknown", this should  
> > happen
> > automatically.
>
> I don't have an unknown account.  I do have a postmaster account.

The postmaster account serves an entirely different purpose than unknown.
Furthermore, postmaster is the one address that SMTP servers are required
to accept mail for, so SIMS requires that it exists.

> > Also, if you have something in your router along the lines of
> > *@domain.com = local.account, then any address for domain.com will be
> > accepted and routed to the local.account specified.
> I do have this routing entry <*@domain.com> = do1-* and domain.com =  
> mail.domain.com.  I have about a half dozen domains that i accept  
> mail for.

By itself, that shouldn't cause you to accept messages to unknown addresses
(for mail addressed to joe@domain.com to be accepted, the local account
do1-joe must exist). Do you by any chance have a router entry that routes
<unknown> to a existing account? E.g.:

<unknown> = existing-account-name

The default SIMS set-up should reject mail to unknown addresses. If memory
serves*, the only ways to get SIMS to _accept_ mail to unknown addresses
are:

- Create an account named 'unknown'

- Create a router entry that routes <unknown> to an existing account
(<unknown>=existing-account-name)

- Create a router entry that routes *@domain to an existing account without
a wildcard, where 'domain' is a domain that you accept mail for
(<*@domain>=existing-account-name)

In general, it is desirable to reject messages to unknown addresses in your
local domains.

> I am getting a queue full of things addressed to bogus usernames AND  
> domains that i don't service.

Aha. This, combined with your other question about 'NULL emails' turns on a
light. It sounds like the messages in your queue are bounce messages
generated by your server and being sent to the 'bogus' addresses, which are
actually the envelope senders of the messages being bounced. Open the queue
files in a text editor to confirm. They may, in fact, be bounces of
messages that were sent to unknown addresses in your domains.

>  I want sims to reject those and not even receive them even though
>  they are sitting in the queue and will eventually be deleted.

SIMS is _sending_ these messages, not receiving them, so the notion of
rejecting them doesn't make sense. You _want_ your own server's bounce
messages to be delivered if possible, so you should want these message to
remain on your queue until they are either delivered to whatever MTAs are
responsible for their recipient addresses or otherwise disposed of
(rejected by the recipient MTA, etc.).

If you don't want to bounce messages to unknown addresses, and thus avoid
having your queue fill up with bounce messages for them, you can route
<unknown> to null with:

<unknown> = null

With this, SIMS will accept messages to unknown addresses, but will not
deliver them to any real account. I.e., they're routed into the ether. This
may sound like something you'd want to do, but it has an undesirable side
effect. Since a message routed to null is accepted and no bounce message is
sent, it will appear to the sender that the message was delivered.

In the case of legitimate mail that is misaddressed due to typos and the
like, you should want a bounce message to be sent so that the sender can
correct the address and re-send.

In the case of dictionary attacks from address harvesters, you arguably
don't want the sender to think that messages are being accepted because
they will take it as confirmation that they are sending to valid addresses.

> I don't have any entries in the router to delete anything.  Do i need  
> some of those?

No. I think that your server is probably not accepting mail for unknown
addresses and that's a red herring. In fact, it's likely that your server
is doing the right thing. To confirm that you are rejecting unknown
addresses, try sending to a non-existent address in one of your domains.

* I am no longer running a SIMS server, although I did for several years,
so this is all from memory. Corrections are welcome.

--
                   Christopher Bort | cbort@globalhomes.com
            Webmaster, Global Homes | webmaster@globalhomes.com
                      <http://www.globalhomes.com/>
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