Edit 3/27/17:  Rather than add another post, this entry has been updated to reflect the addition of the Find Groups button added for group mirroring.

When automating distribution lists, eventually someone will want one that doesn’t use its own filter, but contains the same members as another group.  (Usually it is a security group when there is separation between DLs and security groups.)  The module has always supported group mirroring, but it required a specific syntax (the LDAP filter had to be prefixed with “guid:”) and that the object’s GUID be entered (without curly braces).

The module has been updated so that it is much easier to use group mirroring.  The GUI now has a separate field for entering the groups to mirror:

You select the radio button for either using an LDAP filter or mirroring the membership of other groups.  You no longer manually enter the GUID of the object, but enter the distinguished name of the object and it will be converted to the objectGUID when saving the filter.  (Using the objectGUID allows membership updates to continue even if the source group is moved and its distinguished name changes.) You can also add groups to the list by clicking the Find Groups button and searching for them.  This functionality is provided by an external library that is included in the download.  Put the DLL in the same directory as the module and it will automatically be loaded.  I have added a check for the library, so if it isn’t found, the Find Groups button will simply be disabled and a label will be displayed next to it that says the dependent file could not be loaded.

When running Get-AutoDLFilter and Set-AutoDLFilter, the objectGUIDs will be converted into the current DNs for display.  The GUI output of Get-AutoDLFilter has also been updated to reflect whether it is using an LDAP filter or group mirroring and, if the latter, doesn’t display the sections for the display-formatted and raw filters.

The distinguished name of the object(s) will be validated when the focus leaves the text box (unless clicking the Cancel button), checking that it resolves to an existing group object.  If updating a group’s filter from the command line, the MirrorGroup parameter has been added to the Set-AutoDLFilter cmdlet.  The same DN validation occurs when updating from the command line, and the LDAPFilter and MirrorGroup parameters are in separate parameter sets so that they are mutually exclusive.

Any existing groups using group mirroring are compatible with this version:  Nothing has changed on the “back end,” only how the groups being mirrored get added to a filter has been updated.

Download the module and AD object picker library here:

  AutoDLManagement.zip (22.7 KiB)

If you want just the module, it is here:

  AutoDLManagement.psm1 (55.4 KiB)

I have spent a fair amount of time updating the AutoDL module I first posted back in December.  At the end of that post I mentioned several things I was considering adding, and that made me want to add some of them.

• You can now specify users that should always be excluded even though they match the filter:
  

  The ability to exclude users from membership is now an option.

  The Set-AutoDLFilter cmdlet has also been updated with the AlwaysExclude parameter.

• LDAP syntax checking has been added and occurs when the focus leaves the filter’s text box:
  

  LDAP syntax will be validated and present a warning if it does not pass.

  The OK and Preview buttons will be disabled if the syntax check fails.  I looked around for ways to simply and efficiently validate syntax, but I could not find anything besides what is provided via the LDAP interface to Active Directory.  When performing an LDAP search, a specific error is returned if the syntax is not valid, so the module passes the entered filter to AD and checks the response.  (For efficiency with filters that pass, I use the FindOne() method so the search will stop as soon as the first matching object is found.)

• A preview window has been added:
  

  Clicking the Preview button opens a new window to show who will be in the DL.

  The preview window will display a sorted list of member display names.  You can copy this list to the clipboard to be able to, for example, paste pending membership into an email of the person requesting the DL for confirmation.  There is also a field that provides the membership count.  If the filter results in no members, the count field will contain a hyphen and the Copy button will be disabled.

• A parameter, VerboseMembershipChanges, has been added to Update-AutoDL if you want to include in the output (screen and log file) the individual members that were added and removed:
  

  You can get detailed membership changes in the screen output and log file.

• The Verbose parameter can be used with Set-AutoDLFilter and Update-AutoDL to get more details of activity.  I added a bunch of Write-Verbose commands while I was debugging these recent changes and I left them in for those that want more information about what is happening.
• The module has been updated to conform with the recommendations of the PSScriptAnalyzer module.
• The module now requires PowerShell version 3 or higher and will check for that.
• Several (well, more than several) minor fixes as a result of previous changes made that weren’t discovered until I was testing in a new lab and had to create new DLs and provision them and do other tasks that are less common once you are only maintaining automated DLs.  This is what modules like Pester are for, I suppose.

You can download the updated module with this link:

  AutoDLManagement.psm1 (55.4 KiB)

(I have started exploring the possibility of hosting a Nuget repository or publishing my modules on the PowerShell Gallery so PowerShell v5+ users can simply install them with a command like Install-Module AutoDLManagement -force.)

Years ago I used a third-party application for creating, managing, and updating automated DLs in Exchange.  When I moved to another company that didn’t have that application, nor would spend the money to buy it, I wrote a script as a poor-man’s version of that application.  Since then, it has been updated with more features, and I recently updated it again for a customer who wanted features I had never needed.

You might wonder why not use dynamic distribution groups?  There are a number of limitations when using DDGs that automated DGs (née DLs) overcome:

• Use the group as a security principal
• Allow static members (those that should be members even though they don’t match the filter)
• Use any LDAP attribute in the schema in the search filter, not just those exposed via OPATH
• View the group membership (when an end user)

The way the module works is it marks an existing DG as automated and updates the Note property stating that it is an automated group; you enter an LDAP filter to use for membership, optionally specifying any static members and domains to restrict membership to, and save it; and the membership criteria are saved as a binary value in the extensionData attribute.  Then you can run Update-AutoDL to update the membership of that one group or all (or all in a specified domain), or schedule a task to run that cmdlet to update membership, say, daily.  If you want to download it without reading all of the details:

  AutoDLManagement.psm1 (55.4 KiB)

Prerequisites:

• Permission to manage the group objects in Active Directory
  The module uses ADSI to manage the groups, search for members, and to update membership.
• A shell with Exchange cmdlets loaded
  A few of the Exchange cmdlets are used to validate that a group exists, and to enable it for automation.

Installation:

• Put the module in an appropriate directory
  If you want the module to be implicitly loaded, or explicitly loaded without specifying a path, put the module inside a directory of the same name inside the Modules directory of your profile, e.g., C:\Users\<username>\Documents\Windows PowerShell\Modules\AutoDLManagement\AutoDLManagement.psm1.  You can put it anywhere if you want to load it manually and specify the full path to it.
• For interactive or scheduled execution, load the Exchange cmdlets
  Whether using implicit remoting or a shell loading the Exchange snap-in locally, you’ll want to have the Exchange cmdlets loaded in the session before running any of the AutoDL cmdlets.

Features of the AutoDLManagement module:

• Uses an LDAP filter as membership criterion
  Note: There is no syntax checking for the filter, so be sure you enter a valid one.
  
• Membership criteria are stored in the group itself
  There is no external dependency except for the module to update the group membership.
• Group can contain static members
  Include recipients that do not match the search filter.  The attribute used to match static members can be customized.  (The default is sAMAccountName.)
• Restrict membership to specified domains
  The default configuration is to include all matching recipients in the forest, but you can specify one or more domains in the forest that membership is restricted to.
• Global filter that applies to all groups
  This is a filter that is applied in addition to a group’s filter, such as not including terminated users.
• Customize which custom attribute (extensionAttributeN) and what text string are used to indicate a group is automated
• Email notification when a group update fails or membership is zero when it wasn’t previously
  If the module is unable to add members after clearing membership, resulting in no members, you are notified so you don’t end up with a group that people are emailing and no one gets the message.
• Supports all versions of Exchange, including Exchange Online
  Note: Exchange Online support requires groups to be authoritative on-premises, syncing to Exchange Online via AAD Connect.
• Display membership criteria in both “raw” and “pretty” formats
  When you run Get-AutoDLFilter, the result is an IE window that displays the LDAP filter, the static members, and domains for membership.  The filter is displayed as both a raw string that you can copy and paste for editing, and as a formatted filter (based on my LDAP-formatting script described here) that can be easier to read and is useful when sending a filter to a user.
  
  
• Mirror membership from other groups
  Sometimes a group owner wants the membership to mirror a security group because it isn’t mail-enabled.  You can mirror membership of one or more groups by setting the LDAP filter to be “guid:<GUID of group>”.  Separate multiple GUIDs with a semicolon.
• Logging of each group that is updated, including old and new count
• Ability to update the membership of one group, all groups, or groups in a specified domain
  When running Update-AutoDL, you can provide the identity of a group, use the UpdateDomain parameter to specify a single domain’s groups to update, or no arguments to update all groups in the forest.  (If you update all groups interactively, it will ask for confirmation.  If updated via a scheduled task, the confirmation is suppressed.)
• Set/Update a group’s criteria via command line or GUI
  Run Set-AutoDLFilter (alias sadl) with the identity of a group.  If the group is not already managed/automated, it will ask if you want to enable it:
  After entering ‘y’, the GUI will display so you can enter membership criteria:
  The form performs basic checks in order to enable the OK button: if static members is checked, then the text box has to be populated; if domain restrictions is checked, then at least one domain must be checked.When you run the cmdlet with a group that already has membership criteria, the form will be populated with the appropriate values, so you only have to modify what is to be changed about the criteria.For command-line updating, use the appropriate parameters for the filter, static members, and domain restrictions.  (The parameters are documented in the cmdlet’s help.)  If you update from the command-line, you need to include all values even if it isn’t changing.  For example, if you are modifying the LDAP filter for a group that has static members, you need to specify those members even if they aren’t changing.  Otherwise, the static members (or domain restrictions) will be lost.
• Pipeline support
  For bulk-enabling and -changing groups, you can pipe groups to the Set-AutoDLFilter cmdlet.  This allows you to bulk-enable groups for automation and set their membership criteria if you already have that information in, say, a CSV.  You can use a switch parameter with the cmdlet to suppress the confirmation prompt to enable automation for a group.

Functionality that I am considering adding in the future:

• Static exclusions (Now Added)
  If there are recipients you don’t want to be in the group even though they match the criteria, you can specify them.  (You can do this now by adding the username to the filter with a NOT operator, e.g., (!samaccountname=johndoe).)
• Add object picker for selecting groups for mirrored membership
  Currently, you need to manually enter the source group’s GUID in the LDAP filter field (preceded by guid:).  The object picker would let you browse the forest and select a group to have its GUID automatically entered.
• Perform syntax checking of an LDAP filter (Now Added)
• Preview the pending membership of a group (Now Added)
  In the criteria editor, you could click a button to preview the membership based on the criteria currently specified (and without having to save it).
• Add/remove only changed members (Module already does this)
  Currently, group membership is cleared and then updated with all objects returned in the search.  This has an element of risk because if a failure occurs between clearing and adding membership, the group is left with no members.  This feature would compare the current and pending memberships and only add/remove the necessary objects.

If these or other features would be of interest to you, let me know in the comments.  Download the module:

  AutoDLManagement.psm1 (55.4 KiB)

A small update has been made so that comparing delegates to users with Full Access and Send As works for Exchange Online accounts. The code to translate a user ID to a SID returns an error when used against Exchange Online. If the connection mode is for Exchange Online, it will now use SMTP address to match a delegate to a user with Full Access and Send As permissions. Download the updated module here:

  DelegateManagement.zip (9.2 KiB)

I spent some time figuring out why calendar items in the Deleted Items folder that would be immediately expired could not be updated with a tag. I found that Exchange wants to send an update to the organizer, regardless whether the calendar item is even a meeting or one that is in the past. If the item is in a different folder when the tag is applied, the error is that there is no recipient on the message, whereas the error when in the Deleted Items is that it can’t update an item that is already deleted. The latter error being misleading is why I originally couldn’t figure it out what they meant or why it was happening.

The solution is to use a second argument in the Update method to tell Exchange not to send an update message for invitations or cancellations. You have to do this even if it isn’t a meeting. Presumably, this is a bug where Exchange is running through logic against all IPM.Appointment-class items, rather than skipping those that aren’t meetings.

The script has been updated to account for this, plus some minor updates since the last version posted.

  Set-DefaultFolderItemsTag.ps1 (9.4 KiB)