We have had a RightFax 9.3 server running with a connector our our Exchange 2003 server for quite a few years and have had no issues. We had to reboot our exchange server the other day because we are at our DB limit. We plan on upgrading to Exchange 2010 in a few weeks. Ever since that reboot, our RightFax connector won't run. We always get the Service couldn't start because of a logon failure. We have unintalled and reinstalled the connector. We have tried local admin accounts, domain admin accounts and the Local System account, they all come back with the same error. Other services are running just fine. The RightFax services have been restared as well as the Exchange server. The fax server runs fine, it's just not sending e-mails to Outlook.
To do the install, you should be logged to the Exchange server on an account that is a member of Enterprise Admins, Schema Admins and Domain Admins.
I haven't found a 9.3 manual, but there is a 9.0 manual here http://www.captaris.com/cms_resources/pdfs/9.0_support_docs/RightFaxMicrosoftExchangeModuleGuide.pdf