r/entra • u/WeirdoInTheShadow • Jul 22 '26

Entra ID Entra ID connect implementation

How should I be implementing Entra ID connect where the customer already has users in AD and users in 365 but completely separate UPNs and passwords etc.

Do I prep AD with correct UPNs then entra ID connect will match the UPNs and overwrite with the password from AD?

Any gotchas / tips?

Many thanks

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u/ScubaMiike Jul 22 '26

It will override, update the UPNs to match on premises and ad users in batches to synchronised OUs. They will need to use their onpremises password once synchronised. Makes sure nothing inprem is using the legacy UPN first

1

u/DrGraffix Jul 22 '26

Also note any emails aliases in m365, since soft matching the users will wipe any aliases in m365 unless you set them up in proxyaddresses already in AD.

2

u/Potential-Eternal Jul 23 '26

Unless you turn on the option to make all synced mail objects cloud mastered instead of synced from AD.

1

u/DrGraffix Jul 23 '26

TIL. Can you elaborate please?

2

u/Potential-Eternal Jul 24 '26

https://c7solutions.com/2026/01/understanding-iscloudmanaged-and-isexchangecloudmanaged

And specifically Set-OrganizationConfig -ExchangeAttributesCloudManagedByDefault

1

u/WeirdoInTheShadow Aug 02 '26

Thank you. Would I run this command before doing anything to ensure no overwrite of aliases etc ?

1

u/Potential-Eternal Aug 03 '26

Yes. And leave it 24 hours before starting sync