Which feature is essential for maintaining email continuity in case of service outages?

Email continuity services are crucial for maintaining email operations during unexpected service outages. These services ensure that users can continue to send and receive emails seamlessly, despite any interruptions in the primary email system. Email continuity solutions often include features such as a failover system or an alternative platform that takes over when the primary email service is down. This minimizes downtime, allowing businesses to continue their communication without significant disruption.

On the other hand, while email encryption, cloud archiving, and spam filtering serve important roles in email security and management, they do not specifically address the need for continuity during service outages. Email encryption protects the confidentiality of messages, cloud archiving provides long-term storage for emails, and spam filtering helps in managing unwanted incoming mail. However, none of these features provide the immediate capabilities to counteract outages and maintain operational continuity like email continuity services do.