Anyone running Exchange in the same environment as Samba 3? I have a samba 3.x domain (samba domain controllers) "DomainA" for most of the users at my company. I have a Windows 2003 domain "DomainB" , for about 6 users. I have also have a Windows 2008 domain , which is used for Exchange 2007 ("ExchangeDomain") . There is no trust between the Exchange domain and the Samba domain. There is no trust between the Exchange domain and the Windows 2003 domain. Each user in domainA or domainB has a separate account in DomainX for e-mail access. Machines are Windows 7 SP1 Pro (most are x64, some are x32.) The machines in the samba domain have the following registry change so they can join the domain [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanManWorkstation\Parameters] "DomainCompatibilityMode"=dword:00000001 "DNSNameResolutionRequired"=dword:00000000 On machines with the registry change (even if removed from the domain) , Outlook 2007 does not remember passwords for the Exchange accounts. Machines with out the registry change don't have this problem. This is not a problem on XP machines. Apart from allowing compatibility with Samba domains, what does the DomainCompatibilityMode registry change actually do? Or why it would cause problems with Outlook? Thanks