We have setup external users in external domain that we have specified a Preferred Email ID (@internet domain name) and Internet domain name and checked on both boxes. We have found that sometimes it will send to the Ojbect ID@internet domain name and not preferred email ID@internet domain name. Anybody else seen this issue and have any idea how to fix it. It happens infrequenctly. Here is my setup:

Windows 2003 R2 with GroupWise 8.0.2

Windows XP with either GW 7.0.3 (HP2 to HP3) or GW 8.0.1