Which of the following should be considered when implementing security measures for email?

Implementing DNSBLs (Domain Name System Blackhole Lists) for filtering is an effective security measure for email as it helps to identify and block emails coming from known spam sources. DNSBLs function by maintaining lists of IP addresses that have been reported for sending spam. When an email is received, the email server can query these lists to determine whether the sending server is a known source of malicious or unwanted emails. By utilizing this filtering mechanism, organizations can significantly reduce the amount of spam that reaches their users, thereby enhancing the overall security and hygiene of their email systems.

This approach not only protects users from potential phishing attacks and malicious content but also helps in maintaining the integrity of the email communication channel by ensuring that legitimate communications are prioritized and spam is filtered out effectively. Implementing such measures is crucial in an age where cyber threats are increasingly sophisticated and prevalent.