Autopilot mail to distribution list in Outlook client

For several years I had a report scheduled by Autopilot, sending reports to a distribution list in Outlook.
Granted, it was Jet 5 and Outlook 2003 on XP, but it worked!
I had to upgrade (something about XP :)) and now I use Jet 14 with Office 2007, but the Autopilot logs tell me Jet was unable to send the report to the designated mail address.
As a mail address I use the name of a distribution list that I maintain in the Outlook address book.
There are no spaces in the list name, but there is also no @-sign.
Other autopilot reports that are sent to 1 or more e-mail addresses are doing fine.
So something in the new Autopilot doesn't like distribution lists in Outlook as an e-mail address.

Any help would be greatly appreciated!

rmw

PS. I do not use the SMTP to send mail. The Outlook client is open with the correct profile.