0365 - missing email alias and missing mailbox

Hi InfraAdmin17,

Thanks for posting in our forum. Here for your concerns:

1. If the user password has changed, you need to re-sync this user to let the new password work in online.

2. This situation could be using OU Based filter in AAD Connect sync. Admins can control which objects appear in Azure Active Directory (Azure AD) from your on-premises directory by using by using filtering. When a user moved to an un-sync OU, this account would be soft deleted from Exchange online. It will show again after to move back.

To force AAD Connect sync, you can use the following cmdlets:

Start-ADSyncSyncCycle -PolicyType Delta

Start-ADSyncSyncCycle -PolicyType Initial

However, domain admins don’t have permissions to run the above cmdlets. You need to be an Enterprise Admin to run it. For your reference: Azure AD Connect: Accounts and permissions. Therefore, you can contact your admin to run it.

I hope this can help. Please feel free to let me know if you need any further assistance.

Best Regards,

Sylvie

Hi Sylvie,

Appreciate your response.

Thanks for the info,  that explains everything except part of point 1. I understand resync but It didn't explain how could a user email aliases of old domain gets removed by the password change.

Thanks again.

Hi InfraAdmin17,

Thanks for your reply. Normally, a user email aliases of old domain does not gets removed by the password change. May I know if the old domain is verified both in Office 365 and your AD? If the old domain doesn’t add to you on-prem AD, it will removed from online after the sync, you can double confirm if the old domain alias are added to the proxy address in your on-prem AD.

Best Regards,

Sylvie

Hi InfraAdmin17,

Have you checked if the above reply was helpful? Any updates are appreciated.

Best Regards,

Sylvie

Hi Sylvie,

I confirm, the old domain is verfied both online and On-prem, alias is added to on-prem AD again ( it was added before as well ) which synced across but still unsure how it was removed at first place.

Hi InfraAdmin17,

Thanks for coming back to us. Given your situation, you can use AAD Connect to look into this. When an object doesn’t sync to AAD, you can check the operation logs to find errors identified by the synchronization engine during import and synchronization. Or the connector space to find missing objects and synchronization errors and metaverse to find data-related problems.

For more information about how to troubleshoot it, you can refer to the following article:

https://docs.microsoft.com/en-us/azure/active-directory/hybrid/tshoot-connect-object-not-syncing

Best Regards,

Sylvie