Forum Discussion
Local domain mailbox migration error
I ran into an issue while migrating from on-premise to O365.
On-premise AD domain is “domain.local” so users have their mailboxes smtp address as follows:
primary smtp mailto:email address removed for privacy reasons ( public domain )
aliases smtp proxy: mailto:user@domain.local
We setup the hybrid environment and started the mailbox migration but they’re failing with the error that domain.local is not an accepted domain in O365.
this is the first time it occurred to us since we made a lot of migration so far
What can it be ?
obviously is not possible to add domain.local as accepted domain in o365
8 Replies
That happens because domain.local aliases are syncing to O365, but O365 doesn’t accept non-routable domains. You’ll need to remove or filter out the *.local proxy addresses from AD/Azure AD sync before migrating, leaving only valid routable SMTP domains.
The error occurs because O365 cannot accept internal-only domains like domain.local. Mailbox migrations fail if the mailbox’s primary SMTP or proxy addresses include domain.local, since Office 365 only allows verified public domains. To fix it, ensure all SMTP addresses in Exchange (primary and aliases) use a valid public domain, and keep domain.local only as the legacyExchangeDN/internal routing address. Then retry the migration.
The domain.local format is not supported in the online environment.
Only officially purchased domains are supported.
You must add a public domain(UPN suffix) in the Active Directory Domains and Trusts console and then change all user accounts to the public domain(UPN suffix).I know that, but I'm talking about the "AD internal domain" which is by default added to all exchange users created.
Each user has his primary SMTP address as user @ domain.com which is the public domain and an alias pointing to the AD domain domain.local.
We made several migration and never happened that the internal AD domain was rejected during the migration
It's only added by default becasue you have the .local address in your email address policy. Update the email address policy to remove the .local address, then you'll need to run a script to remove the .local address as an alias from all existing accounts (removing the .local address from the address policy will not remove it from existing objects, it just means any new objects will not have the .local address).
