[Email DLP] Using Groups Containing External Addresses with Directory Synchronization

Question

Directory synchronization is being performed between Microsoft 365 and Email DLP.
To configure an exception Filter for a specific Recipient, I created a Microsoft 365 group that contains the Recipient's email address.
However, the relevant Recipient is not reflected in the synchronization results in Email DLP. How can I have it Synced?

Answer

If you want to include an external email address in the scope of directory synchronization, it must be one of the following types.

• Guest user (shown in Exchange as a Guest Mail User)
• Mail user

Please register or change the external email address by following one of the procedures below.

Configure as a guest user

1. Access the Microsoft Entra admin center at [Users] - [All users] using a user account with Global Administrator privileges.
   https://entra.microsoft.com/ (external link)
2. Click [+ New user] - [Invite external user], and register the external Domain email address.
3. Accept the invitation sent to the registered email address, then complete the registration by entering the one-time code.
4. From [Groups] - [All groups] in the Microsoft Entra admin center, select the Target group.
5. From [Members] - [Add members], Add the registered guest user as a member.
   Note: After registering a guest, it may take some time before it appears.
   If the registered guest user is not displayed, please wait a while and try again.
6. Create Synced Address Group, or if one has already been created, update the group from [Sync Now].
   [Email DLP] Address Settings - Create Synced Address Group / Edit

Configure as a mail user

1. Access the Exchange admin center as a Microsoft 365 Global Administrator.
   https://outlook.office365.com/ecp/ (external link)
2. Open [Recipients] - [Contacts], then click [Add a mail user].
   Note: Do not select "Mail contact," because it will not be Synced.
3. On the Basic Information settings screen, register the Target external Domain email address in [External email address].
   For the other fields, please enter any desired values.
4. From [Groups] - [All groups] in the Microsoft Entra admin center, select the Target group.
5. From [Members] - [Add members], Add the registered mail user as a member.
   Note: After registering a mail user, it may take some time before it appears.
   If the registered mail user is not displayed, please wait a while and try again.
6. Create Synced Address Group, or if one has already been created, update the group from [Sync Now].
   [Email DLP] Address Settings - Create Synced Address Group / Edit

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