Exchange 2000 Server Being used to relay SAPM - Microsoft Exchange

See reply to your other post.

Steve Louie wrote:
> I have Exchange 2000 Server SP3 on Windows 2000 SP4. There
> are message in my Exchange Queues going to domain names
> are are random and are not being sent from any users
> within our domain. When I open the property of these
> messages, it states that it's sent from
> postmaster@mydomain.com with an Envelope Recipients as
> SMTP: very-randon@random.com. I get about 75 messages a
> day and want to know where these messages are coming from
> and how.
>
> First, where is the e-mail postmaster@mydomain.com address
> come from? It's not anywhere on my server.
>
> Second, I have the Default SMTP Virtual Server set to
> default, which MS calims, Open relay is closed. Right
> now, it's configured according to MS KB article 310380 and
> 310356.
>
> Users receive many SPAM mails. one of the user receive
> SPAMs that are sent to (on the TO filed) an e-mail address
> that is not in our network and yet it's going into his
> mailbox, example, billy@mydomain.com. I don't see that
> the message was BCC either. How is this occuring?