Jeffrey Williams (3/25/2009)
Find and edit the file rsreportserver.config. Locate the section for the Report Server Email extension. Modify the default host name and permitted host name sections and add your domain information.Example:
<DefaultHostName>domain.company.com</DefaultHostName>
<PermittedHosts>
<HostName>domain.company.com</HostName>
</PermittedHosts>
Restart Reporting services to pick up the changes.
did not know this trick, thanks for sharing
will keep this in mind
but for my sake, I always explicitly state the full email address anyway