I created a new dynamic distribution group; I confirmed the filter syntax in both the console and the shell; they each show 791 recipients. However, if a message is sent to the new group the expand line of the message tracking log is empty and no one ever receives the message. Other DDLs in the org work as expected.TBrennan

Apparently just because you can retrieve a list of users from the Preview tab or from a set of powershell commands doesn't mean the DDL really has any members. My problem was the recipientcontainer parameter. I didn't think it applied because all the docs I have seen indicate you will not see anything in the preview and I always did. it appears the preview function is useless, the only way to really see what will happen is send a test message to a newly created DDL.TBrennan