Email cannot be sent because the email address of the mailbox requires an approval by an Office 365 administrator

When you attempt to Test and Enable a mailbox in Dynamics 365, one of the following alerts is logged:

• Email cannot be sent because the email address of the mailbox <Mailbox Name> requires an approval by an Office 365 administrator. The mailbox didn't synchronize. The owner of the email server profile Microsoft Exchange Online has been notified.

      Email Server Error Code: OutgoingEmailS2SApprovalNeeded

• Email cannnot be received because the email address of the mailbox <Mailbox Name> requires an approval by an Office 365 administrator. The mailbox didn't synchronize. A notification about this is posted on the alerts wall for the owner of the email server profile Microsoft Exchange Online.

     Email Server Error Code: IncomingEmailS2SApprovalNeeded

• Appointments, contacts, and tasks can't be synchronized because the email address of the mailbox <Mailbox Name> requires an approval by an Office 365 administrator. A notification about this is posted on the alerts wall for the owner of the email server profile Microsoft Exchange Online.

     Email Server Error Code: ExchangeSyncEmailS2SApprovalNeeded

When using Dynamics 365 (online) with Exchange Online, the email address for a mailbox record needs to be approved by an Office 365 user with the Global Administrator or Exchange Administrator role.

1. Sign into Dynamics 365 (online) as a user with the following privileges:

• Global Administrator or Exchange Administrator role in Office 365
• System Administrator role in Dynamics 365

2. Navigate to Settings and then click Email Configuration.

3. Click Mailboxes.

4. Change the view from my My Active Mailboxes to Active Mailboxes.

5. Select the mailbox and then click the Approve Email button.

6. After the mailbox is approved, you can select the mailbox and then click the Test & Enable Mailboxes button.

NOTE: If the test results are something other than success, you can open the mailbox record and click the Alerts section. View the details of any errors that were logged.

For more information on recent changes to approval requirements including how to disable this requirement, refer to the following article:

https://support.microsoft.com/help/4506139