How to set up SMTP Auth using POP3 Global Mailbox on Exchange 2003

We recently had a customer get a bounce-back from Spamhaus, it complained that he had sent the email without SMTP Authentication. Now, setting this up on a standard POP3 mailbox in Outlook is no problem, the issues start when we have to set it up using Exchange.
They currently have a root@ POP3 account being received by the server which then gets distributed accordingly.
How do we turn on SMTP Authentication for all emails going out from the server?

Server OS: SBS 2003
Exchange: Exchange 2003 SP2
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BusbarSolutions ArchitectCommented:
By default SMTP send emails (server to server) with no authentication,  i am missins something can you explain the issue little more
Olaf De CeusterCommented:
Exchange uses DNS or Smarthosting for sending. You can use authentication on smarthosting but not on DNS as far as I know.
Seems a very strange question.
If spamhaus picks up your client you're most probably an open relay or you have a virus.
Have a look at the following:
Hope that helps,

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