1. Open the Mimecast App from Applications

2. Click the Managed Senders icon

3. In this window, you can whitelist and block senders or change the status of senders or domains. 

In the Permitted tab, click Add and enter the email address of the sender or the domain you want to whitelist.

In the Blocked tab, click Add and enter the email address of the sender or the domain you wish to block. 

To view emails that are held by Mimecast, click on Personal On Hold. Right click on the email. 

From here you can release, delete, reject and block senders.

Release – allow to receive email from the sender once

Release and Permit Address – allow to receive emails from the sender automatically  

You can also report Spam or Phishing emails directly to the Mimecast security team by using the Report button.