This happens because the Delay Send option is set to apply only to external emails. To change this, follow these steps:
Step 1: Log in to the SendGuard Management Console
Step 2: Click on M365 settings
Step 3: Enable Delay Send to All Recipients
Article ID: 366, Created: 7/30/2025 at 9:08 PM, Modified: 9/29/2025 at 8:20 PM