How To – Mimecast
Block external email sender
2. Click on Administration Console
3. On left side select “Email Security”
4. Select “URL Protection”
5. On URL Protection page, click on URL Tools > Managed URLs
6. Click Add Managed URLs button
7. fill in the Managed URLs form.
Override type : Blocked URLs
Rewriting : disabled
Match type : Explicit
URLs : <enter the URL to be blocked>
Comment : <add comment why the URL is being blocked>
8. The URL will be added into the blocked list