Blocked Senders policies define criteria for automatically blocking an email. By default, you will automatically have a policy scoped for the default Blocked Senders Profile Group. If you simply need to block another address or domain for your whole account, you should add it to that Profile Group.
Example of use cases for this policy include preventing users from receiving external emails or preventing users from emailing to certain domains.
When an email is blocked by Mimecast, its content is not kept, so cannot be released or recovered by Mimecast.
Note: You must enter the IP Ranges in CIDR format (For single IPs add /32 at the end)
A Blocked Sender policy will always apply before a Permitted Sender policy, so a whitelisted sender may still get blocked by these policies.