I have a situation where I have 13 separate domains who want to share a single exchange domain (resource type domain). 10 of the domains are either 2003 or 2008 full server, which causes no problem. However 3 of the domains are SBS 2003 or SBS 2008 domains. As I understand it SBS cannot trust another domain. I presume that this lack of trust ability would mean that the 3 SBS domains would have to upgrade to full server domains

Hi, You are correct SBS does not have the abillity to create a trust relationship. You can provide access to a mailbox via OWA or Outlook anywhere, but the user has to have two seperated accounts and provide both credentials. But it is possible Regards Ronny