TheGeekery

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Exchange 2010, 2013, and Office365: Dynamic Distribution List Filters

In our transition to using Offce365 for email services, we’ve had some interesting discoveries. Some of them are revolving around Dynamic Distribution Lists (DDLs). These are groups which have members identified at time of delivery of emails, and are based on various styles of queries. We usually use PowerShell style queries to build the groups, but LDAP works, as does simple queries based on fixed parameters.

One of the interesting observations is that Exchange will tack extra query parameters into the DDL to exclude system mailboxes. For example the following query string:

(RecipientType -eq 'UserMailbox') -and (CustomAttribute4 -eq 'Plano')

Will actually result in the follow query:

((((RecipientType -eq 'UserMailbox') -and (CustomAttribute4 -eq 'Plano')) -and (-not(Name -like 'System{*')) 
-and (-not(Name -like 'CAS_{*')) -and )-not(-not(RecintTypeDetailsValue -eq 'MailboxPlan')) 
-and (-not(RecipientTypeDetailsValue -eq 'DiscoveryMailbox')) 
-and (-not(RecipientTypeDetailsValue -eq 'ArbitrationMailbox')))

This forces Exchange to exclude any of the system mailboxes for delivery, which is what you want it to do. The problem is, this additional data varies from version to version, and it’s not always backwards compatible. One of the observations is that in Exchange 2013 they introduced a RecipientTypeDetailsValue of PublicFolderMailbox. This is great, except that value is invalid in 2010. What does that mean?

Let’s try an example. From one of our on-prem 2013 hyrbid servers, we’re going to create a new distribution group with the initial query we gave as an example above…

New-DynamicDistributionGroup -Name 'JATestDist' -RecipientFilter "(RecipientType -eq 'UserMailbox') -and (CustomAttribute4 -eq 'Plano')"

Now it’s created, lets see what we have for a query parameter:

PS C:\> Get-DynamicDistributionGroup -Identity 'JATestDist' | Select RecipientFilter | fl


RecipientFilter : ((((RecipientType -eq 'UserMailbox') -and (CustomAttribute4 -eq 'Plano'))) -and (-not(Name -like
                  'SystemMailbox{*')) -and (-not(Name -like 'CAS_{*')) -and (-not(RecipientTypeDetailsValue -eq
                  'MailboxPlan')) -and (-not(RecipientTypeDetailsValue -eq 'DiscoveryMailbox')) -and
                  (-not(RecipientTypeDetailsValue -eq 'PublicFolderMailbox')) -and (-not(RecipientTypeDetailsValue -eq
                  'ArbitrationMailbox')))

As we can see, a whole bunch of extra options, including our PublicFolderMailbox option. Lets test to see what users we get back…

[PS] C:\>$dist1 = Get-DynamicDistributionGroup -Identity 'JATestDist'
[PS] C:\>Get-Recipient -RecipientPreviewFilter $dist1.RecipientFilter
$dist1 = Get-DynamicDistributionGroup -Identity 'JATestDist'
Get-Recipient -RecipientPreviewFilter $dist1.RecipientFilter

Name                                                        RecipientType
----                                                        -------------
Angliss, Jon                                                UserMailbox

Okay, so we get results back, no big deal right? Now I’m going to go to a 2010 server, and without changing anything, I’m going to see what results we get back…

[PS] C:\>$dist1 = Get-DynamicDistributionGroup -Identity 'JATestDist'
[PS] C:\>Get-Recipient -RecipientPreviewFilter $dist1.RecipientFilter
The recipient preview filter string "((((RecipientType -eq 'UserMailbox') -and (CustomAttribute4 -eq 'Plano'))) -and (-not(Name -like 'SystemMailbox{*')) -and (-not(Name -like 'CAS_{*')) -and (-not(RecipientTypeDetailsValue -eq 'MailboxPlan')) -and (-not(RecipientTypeDetailsValue -eq 'DiscoveryMailbox')) -and (-not(RecipientTypeDetailsValue -eq 'PublicFolderMailbox')) -and (-not(RecipientTypeDetailsValue -eq 'ArbitrationMailbox')))" is neither a valid OPath filter nor a valid LDAP filter. Use the -RecipientPreviewFilter parameter with either a valid OPath filter string or a valid LDAP filter string.
    + CategoryInfo          : InvalidArgument: (:) [Get-Recipient], ArgumentException
    + FullyQualifiedErrorId : 79B22B5B,Microsoft.Exchange.Management.RecipientTasks.GetRecipient

Now we see an error. This is because 2010 doesn’t like PublicFolderMailbox as a RecipientTypeDetailsValue, and as such, throws it out as an error. So we have to go back to the 2010 server and edit the query, and reset it to be what we wanted originally:

[PS] C:\>Set-DynamicDistributionGroup -Identity 'JATestDist' -RecipientFilter "(RecipientType -eq 'UserMailbox') -and (CustomAttribute4 -eq 'Plano')"
[PS] C:\>$dist1 = Get-DynamicDistributionGroup -Identity 'JATestDist'
[PS] C:\>Get-Recipient -RecipientPreviewFilter $dist1.RecipientFilter
$dist1 = Get-DynamicDistributionGroup -Identity 'JATestDist'
Get-Recipient -RecipientPreviewFilter $dist1.RecipientFilter

Name                                                        RecipientType
----                                                        -------------
Angliss, Jon                                                UserMailbox

This same query is happy on the 2013 servers as well, however, it will attempt delivery to a Public Mailbox if your other query parameters allow for it. In the example above, we set the RecipientType to be a very specific value, so this shouldn’t allow for this to happen anyway.

One other observation, when migrating your queries to be Office 365 Hybrid complaint, you will also need to include the RecipientType of MailUser. For example:

((RecipientType -eq 'UserMailbox') -or (RecipientType -eq 'MailUser')) -and (CustomAttribute4 -eq 'Plano')

Mailboxes that are migrated change their RecipientType to be MailUser.

There are lots of other fun things about DDLs that you’ll have to be aware of, which I shall cover in a separate post, but this is one of the fun gotchas I discovered in a mixed environment that’ll impact people using Exchange 2010 and 2013 in the same environment.

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