There are several caveats here. It is possible that a Security group has an
email address and it is possible that a distribution list does not have an
email address assigned. To get a truly
comprehensive picture we would have to create a CSV file from the 3d report of
all distribution groups, create a CSV file from the 3a report just looking for
Groups embedded in groups, and then use Excel or PowerShell to merge the data
to identify the distribution group members.