At least share the FILENAME and any ODS statement information. Ideally it would be best to COPY/PASTE the SAS-generated log output where the fully-expanded SAS code is generated and any diagnostic messages are displayed. Someone may try to guess that you do not have a domain name listed in your destination EMAIL address, based on the ERROR you have shared in your post -- best to be sure by sending the log output intact for good feedback. Also, SAS version info with service pack or "phase" (SAS 9.2) helps a lot as well.
Lastly, the presumption is that you can send EMAIL with the same format using some other EMAIL client on the same machine with VISTA, right?
Scott Barry
SBBWorks, Inc.