Securing Exchange Server (2003) - What do you do? SPF?

[Major_Disaster]

Hello,

Im just playing around with SBS 2003 in VMware Workstation and was wondering what post installation steps you take after installing vanilla Exchange Server 2003 SP2.

Ive got antispam software installed and have just setup the SMTP banner. What about SPF? Ive added the TXT record into the DNS (via the registrar's control panel) - is this ok: v=spf1 mx:mail.domainco.uk ~all

What else should i be doing? What other steps do you take with your mail servers?

Cheers

 

[Major_Disaster]

Thanks. Im playing around with Sophos PureMessage and am pretty impressed with it.

Was more wondering though Exchange specific settings (such as IMF etc) rather than comparing various antispam products.