Entra Connect synchronizes on-prem accounts to Microsoft 365. This means when the two synchronizes, on-prem accounts will be created in Microsoft 365. If there are on-prem accounts and Microsoft 365 accounts beforehand that are not synchronized, this can cause issues. To resolve the issue, go onto AD DS and select attribute editor for these accounts. Go to proxyAddress and write “SMTP:<Email address of Microsoft 365 account>”. This will synchronize the appropriate two separate accounts.

  1. Log into the admin portal of Microsoft 365 and got to Identity. Under Entra ID, select Entra Connect. Select Manage and download connect sync agent

  2. Run Azure Ad Connect. Customize settings and select Install with nothing selected.

  3. At User sign-in select Password Hash Synchronization.

  4. Enter Global Administrator M365 Credentials

  5. Click add directory

  6. Create a new AD account and input an enterprise admin account

  7. Select Next

  8. Select Continue without matching all UPN suffixes to verified domains. Click Next

  9. Click Next

  10. Synchronize all users and devices. Click Next

  11. Click Next

  12. Install