Preparing Your Environment is built to test anti-malware controls, rather than reputation-based controls. To that end, we recommend that you whitelist the following domain in such a way that reputation-based checks are bypassed, for example anti-spam, but anti-malware controls are still applied.

The address to whitelist is, and all emails are sent from


  • From your Microsoft 365 Defender portal, under Policies & Rules, navigate to Threat Policies and select Anti-spam. Direct link.
  • Select the Anti-spam inbound policy (Default) policy and then scroll to the bottom and click Edit allowed and blocked senders and domains
  • Under Senders, click Manage 0 sender(s) and then Add senders
  • Enter
  • Click Add senders and Done
  • You should have something that looks like this. Once you’re happy, click Save

Spam Whitelist

If emails are still being blocked, contact Support or join us in #support on Slack to get help.


  • Log in to your Mimecast Administration Console.
  • Click the Administration toolbar button.
  • Select the Gateway | Policies menu item.
  • Select Permitted Senders from the list of policies displayed.
  • Select the New Policy button.
  • Select the appropriate policy settings under the Options, Emails From, Emails To, and Validity sections.
  • In the Source IP Ranges field , enter
  • Save the policy