"changes to the distribution list membership cannot be saved. you do not have sufficient permission to perform this operation on this object"

Question

Running Exchange 2010/latest updates on Windows 2008 R2 servers.
When I create a new DL that I want someone to manage, they received the following message when trying to add/remove from the DL:
"changes to the distribution list membership cannot be saved.  you do not have sufficient permission to perform this operation on this object"
I have followed everything in "http://msexchangeteam.com/archive/2009/11/18/453251.aspx" with no luck
Any suggestions?

Answer 1

Piggybacking off of the discussion above, with our deployment of Exchange 2007, we created a set of web-based tools that allowed people to create Exchange Resources including distribution lists.  To allow multiple people to manage the lists for a given
department, we programmatically created a group, which is populated with one or more users from the "resource department".  We then set the following AD permissions to allow members of the group to manage membership of departmental distribution lists:
Add-ADPermission -User DepartmentalGroup -AccessRights ReadProperty, WriteProperty -Properties 'Member' -DomainController dc.contoso.com
Fast forward to Exchange 2010 and the landscape has changed with Exchange 2010's implementation of Role Based Access Control and I'm struggling to come up with a way to programmatically allow a group of users to manage distribution list membership for a
subset of distribution lists - note that we have approximately 75 departments, with each having its own set of coordinators who should be able to manage distribution lists for their department but not lists created by other departments.  The specific
error we receive in Outlook when attempting to modify group membership is the same as the title of this thread - "Changes to the distribution list membership cannot be saved.  You do not have sufficient permission to perform this operation on this object". 
I implemented the settings referred to at
http://sysadmin-talk.org/2010/06/omg-allowing-end-users-to-manage-distribution-group-membership-in-exchange-2010-2/ which details the process of creating a new management role and revoking the role's ability to create new distribution lists and remove distribution
lists (which we want because we want those actions to be performed using our web tools). 
All that to say that the ultimate problem we have is that the above relies on the "ManagedBy" field of a distribution list (viewable by Get-DistributionList Listname | fl *ManagedBy*) to determine group ownership.  When "ManagedBy" is set to a user,
the user CAN edit a distribution list's membership from Outlook and OWA.  When "ManagedBy" is set to a group, members of the group are UNABLE to edit the membership of the distribution list via Outlook or Outlook Web Access/ECP.   Furthermore,
Set-DistributionGroup does not allow you to specify a list of users to assign to the ManagedBy field.  However, if "ManagedBy" was set to a specific user and that user logs in to the Exchange Control Panel and adds additional "owners" of the distribution
list, which I can then see from EMS - both the original owner and any additional owners added can in turn modify group membership for the list using Outlook or Outlook Web Access/ECP.
My questions:
1) Is it "expected" behavior that while I can assign a group to the "ManagedBy" property of distribution list, members of that group are still unable to edit the group membership?  ...or is there a fix for the behavior I'm seeing?
2) Can multiple values be assigned to the "ManagedBy" property when using Set-DistributionList - ex: Set-DistributionList DLName -ManagedBy:user1,user2
3) Any other suggestions?
Thanks,
-Lance