I have run in to a problem with having a Mailbox created that is similar to a PDL, the only difference between the two is one word. What happens is when someone sends to the PDL it either doesn't get sent to the list of mailboxes or it goes to only some of the group.
For example:
Mailbox: cn = Planning Committe Share
PDL: cn = Planning Committe List
The only work around I have found was to either remove the mail box or rename it so the cn = PlanningCommitteList. Changing the email address doesn't work, I have to change the display name.
To me it seems that Scalix can't determine the difference between a Mailbox or PDL, when sending mail.
Running:
Scalix - version 9.2.1
OS - SuSE 9.0 Ent