Which action can be set up to mitigate the risk of future email security incidents?

Blocking known malicious addresses is an effective action to mitigate the risk of future email security incidents. This practice focuses on preventing unwanted or harmful communications from reaching users' inboxes, which can be a significant source of phishing attacks, spam, and other malicious content. By maintaining a blacklist of email addresses that are linked to harmful activities, organizations can reduce the likelihood of their users inadvertently engaging with malicious emails. This helps protect sensitive information, maintains the integrity of the organization's email communication system, and fosters a more secure digital environment.

The other options, while they may have their own merits, do not directly address the ongoing risk posed by malicious communications. For instance, increasing email server storage does not enhance security; it merely allows more data to be stored, which doesn’t resolve the issue of incoming threats. Disabling all email notifications could impede communication altogether and fail to protect against threats effectively. Employing a new email service provider might improve features or support but will not inherently improve security unless proper configurations and security measures are implemented following the switch. Thus, focusing on blocking known malicious addresses is a proactive and targeted strategy in managing email security.