If you are using Microsoft Office 365 to host your mailboxes, it is recommended you follow these steps to to ensure that your organizations instance of Cloud Email Security is not throttled or blocked by Microsoft.
- In the Exchange admin center (EAC) navigate to Protection -> Connection Filter and then double-click the default policy
- Click the Connection filtering menu item and in the IP Allow List, enter the assigned IP addresses found in your Welcome Email
- Save your changes
Please note: The setting may take up to an hour to propagate
You may need to open a ticket with Microsoft to ensure that changes are replicated. There are have been cases where IP Allow Lists are not honored. Please test all changes using a non-production domain before doing a full production cut over.