When you configure Outlook web Access for SSL, you need a certificate to insure the identity of the website.
The most secure way (but not the cheapest) is to use a third party certificate for OWA.
The cheapest way is to create an enterprise CA (free) using windows certificate services. This is fine for a small company, so a self-signed (microsoft cert generated by your ca) will suffice. T
you need to setup an enterprise root ca for your domain:
http://www.isaserver.org/img/upl/vpnkitbeta2/installenterpriseca.htmhttp://technet.microsoft.com/en-us/library/aa998956(EXCHG.65).aspxand then importing this certificate into OWA:
http://search.techrepublic.com.com/search/certificate+and+microsoft+outlook+web+access.htmlIf you need help with this, let me know