What action should the technician take to ensure incoming email is processed by all three email servers?

Updating the MX record in DNS is a crucial step for ensuring that incoming email is processed correctly by all designated email servers. The Mail Exchange (MX) record specifies the mail servers responsible for receiving email on behalf of a domain. When this record is properly configured, it directs incoming emails to the appropriate servers based on the priority levels established in the DNS settings.

When multiple servers are designated for handling email, the MX records can also establish a failover strategy, where if one server fails or is unavailable, the email traffic can be rerouted to another server listed in the MX records. This operation is essential for load balancing and ensuring continuity of email services, particularly for organizations that rely on multiple servers for redundancy and high availability.

Other actions, such as rebooting all email servers, changing the email server settings, or disabling the firewall, may not directly facilitate the proper routing of incoming emails. For instance, rebooting the servers won't ensure they are set up correctly to receive emails, changing server settings could lead to misconfiguration, and disabling the firewall might expose the servers to security risks without addressing the routing of emails through the correct DNS records. Hence, updating the MX record is the most appropriate action to ensure that email traffic is directed correctly to all email servers