Theory question on address book policies

Question

Hello!

https://learn.microsoft.com/en-us/exchange/email-addresses-and-address-books/address-book-policies/address-book-policies?view=exchserver-2019

Address book policies (ABPs) lets administrators segment users into specific groups to provide customized views of the organization's global address list (GAL). The goal of an ABP is to provide a simpler mechanism for GAL segmentation (also known as GAL segregation) in on-premises organizations that require multiple GALs.

Still don't understand the following: if the Default GAL is part of the ABP doesn't that mean the user(s) this policy is being applied to will see ALL receipients in an organization? How it's possible to do the "GAL segmentation" if the whole GAL is also part of the policy???

Thank you in advance,
Michael

Answer 1

Hi @Mikhail Firsov

Thanks for your feedback, I'm afraid we cannot 'segment the Default GAL', ' GAL Segmentation' DOES NOT DELETE any mail enable objects. It just creates a filtered version of the GAL for the user.

We could refer to the previous Exchange version official document which gives detailed steps for the example scenario2. Understanding Address Book Policies

Multiple GALs are necessary. The article here introduces the similar process to meet this need: Notes From The Field – Enabling GAL Segmentation in Exchange Online
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

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Answer 2

You can create multiple GALs and assign them to ABPs as needed. "Default" is just a label in the above, it's the "GAL1" part that matters.

Answer 3

Hi @Mikhail Firsov

We could refer to the introduction of GAL, your Exchange server supports for multiple GALs.

By default, a new installation of Exchange Server creates an GAL named Default Global Address List that's the primary repository of all recipients in the Exchange organization. Typically, most organizations have only one GAL, because users can only see and use one GAL in Outlook and Outlook on the web (formerly known as Outlook Web App).
You might need to create multiple GALs if you want to prevent groups of recipients from seeing each other (for example, you single Exchange organization contains two separate companies).

And you could use different parameters to sepcify what users will be included in this GAL, for example -RecipientFilter
This example creates a GAL with a custom recipient filter:

New-GlobalAddressList -Name "Agency A GAL" -RecipientFilter "CustomAttribute15 -like '*AgencyA*'"  

Details: Global address list procedures and New-GlobalAddressList

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Answer 4

Hello!

Thank you all for your replies!

Yes, I know that an administrator can create multiple GALs (+ OABs) and deploy them via ABP and that does make sense. My question stems from this simple assertion in the MS official curriculum for Exchange Server 2016:

So I'll reformulate my question:

Q: Is it possible to "segment the Default GAL" using ABP WITHOUT creating "multiple GALS" as the textbook says?

Answer 5

"Multiple GALs are necessary." vs "An ABP is an alternative to creating multiple
global address lists. - great textbook :(((

Thank you very much for the help, joyceshen-MSFT!

Regards,
Michael