In my organization we rely heavily on Address Lists within Exchange Online. For several years people have been able to find other people within the organization by accessing the Address book within Outlook or OWA, select the department and find the person that they are looking for.
We have accomplished this by simply creating an address structure that looks similar to the following:
"\Departments" -Addresslist under the root that does not contain any recipients "\Departments\Department1" "\Departments\Department2" etc
All of our Department address lists have a recipient filter similar to the following:
RecipientFilter: MemberOfGroup -eq 'CN=department,OU=tenant.onmicrosoft.com,OU=Microsoft Exchange Hosted Organizations,DC=NAMPR04A092,DC=PROD,DC=OUTLOOK,DC=COM'
Then one day we noticed that all of our Address Lists no longer contained any recipients!
I contacted Microsoft and spent nearly 1 1/2 days on the phone with no resolution. After analyzing my addresslists, I noticed a discrepancy between the RecipientFilter and the LdapRecipientFilter. It has now appeared that Microsoft moved all of my Distribution groups to a new location within their Azure AD domain infrastructure. They did update the RecipientFilter for all of my addresslists to point to the new DistinguishedName of my Distribution Groups , but somehow this did not prevent them from breaking.
The resolution for me was to completely remove all of our custom address lists and re-create them. Even though the RecipientFilter was correct, the LdapRecipientFilter was not correct. And you cannot set the LdapRecipientFilter using the set-addresslist cmdlet.
#Remove all custom address lists under Departments Get-AddressList "\Departments\*" | Remove-AddressList -Recursive
Once all the addresslists had been removed, I simply recreated them using an existing powershell script that is scheduled to run nightly. This powershell script checks for new on-premise distribution groups (mail-enabled security groups, synced with Azure AD), and then creates an address list if it doesn’t already exist.
The final step was to “Tickle” each mailbox and mailuser as described in several articles.
I hope this helps anyone with this problem. Let me know if you came across this problem and what you may have done to fix it. Thanks!