Hello I am having trouble getting Exchange 2003 SMTP Connector Delivery Restrictions to work. I have edited the proper registry entries and restarted the requisite services. I even tried a reboot. I am trying to restrict certain users from using an SMTP Connector. I am unable to add Security Groups as an object into ESM, but can add individual Users and Universal Distribution Lists. These are the edited registry entries in HKLM/System/CurrentControlSet/Services/RESvc/Parameters: Added: CheckConnectorRestrictions REG_DWORD = 1 (hex) Added: IgnoreRestrictionforNullDSN REG_DWORD = 1 (hex) System information: Microsoft Windows Server 2003 Standard Edition SP 1 MS Exchange 2003 Version 2.6.7226.0 The Exchange server is running in MIXED mode. Do I need to set it to Native? If so, can I run exchange in Native mode on a domain with a mixed mode PDC/AD Server? For testing purposes, I set Delivery Restrictions to reject all messages. I can still log into OWA and send mail out. I only have one SMTP protocol and one SMTP connector. Does anyone have any advice on where to look next, or how I should go about debugging this problem? Any comments are appreciated. Thank you. References: http://support.microsoft.com/default.aspx?scid=kb;en-us;277872