Forum Discussion
Adding Proxy Addresses in AD Before Tenant-to-Tenant Migration Cutover
We're in the process of migrating users from another M365 tenant into our own, which is synced with on-prem AD. Before the cutover, we'd like to add the proxy addresses from the source tenant to our AD and have them sync to the cloud once the domain is added to our M365 tenant.
Would this work as expected, or are there any potential issues to be aware of?
Do you have all the corresponding domains added and verified in the target tenant? If not, any aliases associated with them will be replaced with the default onmicrosoft.com domain.
Adding Proxy Address may good but please consider below potential issue as well:
- Attribute Mapping: Ensure that the proxyAddresses attribute is correctly mapped during the synchronization process. Any discrepancies can lead to issues with mail flow and user identification.
- Verification: Verify that the proxy addresses are correctly populated in Microsoft Entra ID (formerly Azure AD). The proxy calculation logic may alter the addresses based on internal rules.
- Reserved Domains: Be cautious of reserved domain suffixes (e.g., @*.onmicrosoft.com). These addresses might be discarded during the sync process.
- Legacy Protocols: Ensure that the proxy addresses do not contain legacy protocols like MSMAIL or X400, as these will be discarded.
- Malformed Addresses: Check for malformed addresses or those not compliant with RFC 5322, as these will also be discarded.
