Exchange Online user to access the on-premises Exchange Control Panel (ECP) - Active Directory attributes

To ensure that an Exchange Online user can access the on-premises Exchange Control Panel (ECP), you need to configure certain Active Directory attributes correctly. Here are the key attributes and steps to point the user to the right on-premises Exchange server:

Key Attributes to Configure:

1. msExchHomeServerName: This attribute specifies the Exchange server that hosts the user’s mailbox.
2. msExchRecipientTypeDetails: Indicates the type of recipient. For a remote user mailbox, this should be set to 2147483648.
3. msExchRemoteRecipientType: Indicates the type of remote recipient. For a migrated mailbox, this should be set to 4.

Steps to Update Attributes:

1. Open Active Directory Users and Computers (ADUC):

   • Enable Advanced Features from the View menu to access the Attribute Editor tab.

2. Locate the User:

   • Find the user account that needs access to the on-premises ECP.

3. Update Attributes:

• msExchHomeServerName: Set this attribute to the FQDN of the on-premises Exchange server.
• msExchRecipientTypeDetails: Set this attribute to 2147483648
• msExchRemoteRecipientType: Set this attribute to 4

Example PowerShell Command:

You can use PowerShell to update these attributes:

# Replace 'username' with the actual username and 'exchangeServerFQDN' with the FQDN of your on-premises Exchange server
Set-ADUser -Identity username -Add @{
    msExchHomeServerName="exchangeServerFQDN";
    msExchRecipientTypeDetails=2147483648;
    msExchRemoteRecipientType=4
}

Additional Considerations:

• Autodiscover Configuration: Ensure that the Autodiscover service is correctly configured to point to your on-premises Exchange server.
• Hybrid Configuration: Verify that your hybrid configuration is set up correctly to allow seamless access between Exchange Online and on-premises environments

These steps should help you point the Exchange Online user to the correct on-premises Exchange server for accessing the ECP. If you need further assistance or have any other questions, feel free to drop me a comment!