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Exchange 2003 SMTP security lockdown procedures

Im using Small Business Server for exchange 2003 mail management.

Periodocially i find that my server is being used to relay messages by spammers.

Is there a consise checklist of security steps i should follow?

1 Solution
Exchange 2003 is relay secure out of the box, so something has been changed.

There are three main ways that an Exchange server can be abused...

- configuration error on the SMTP virtual server or SMTP Connector turns the machine in to an open relay

- authenticated relaying - where the administrator password has been compromised and is being used to allow messages to be sent through the server.

- NDR spam - this is where messages are sent to your server with invalid email addresses on purpose. Your server then tries to bounce them back to the "sender" - who is spoofed and is the real target.

For NDR spam you should deploy recipient filtering and the tarpit.

For authenticated user relaying, you need to look at changing the settings.

Finally, for checking whether the machine is an open relay, see my article here:

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