You should consult the SBS Official Blog on what records to create. This includes an A-Record pointing to the WAN IP address of the router (the internet facing side). This A-Record should match the full domain name you chose in the Internet Address Management Wizard. Then create an MX record pointing to the A record. Additionally, create a TXT record for improving your spam confidence level (of not being spam) to other companies, by creating the TXT record with “v=spf1 a mx ~all”. Finally, for Outlook Autodiscover, you should create a service record of _autodiscover._tcp.FQDN which points to your A record.
For details, consule the official SBS blog post: http://blogs.technet.com/sbs/archive/2008/10/17/introducing-the-internet-address-management-wizard-part-3-of-3.aspx
Posted by Sean Daniel (http://sbs.seandaniel.com)