Employ spam protection mechanisms at information system access entry and exit points.

Spam emails are often malicious. Blocking spam reduces the chance of your users receiving malicious emails.

Implement spam filtering for your email services. Restrict spam from coming into your organization. Restrict your company's email services form being used to send spam (should be mentioned in your acceptable use agreement). Many cloud based email services such as Office 365 Exchange and Gmail have spam filtering features by default. These can be modified to increase their effectiveness. If the spam filters miss any spam email, you should manually add them to the filter.