The recommended alternative to an integrated email encryption system is to encrypt sensitive data separately in attachments. An integrated email encryption system is a system or a service that provides or offers the encryption or the protection for the email messages or the email communications, by using or applying the cryptographic techniques or the mechanisms, such as the public key encryption, the symmetric key encryption, or the digital signatures. An integrated email encryption system can protect the confidentiality, the integrity, or the authenticity of the email messages or the email communications, as it can prevent or reduce the risk of unauthorized or inappropriate access, disclosure, modification, or spoofing of the email messages or the email communications by the third parties or the attackers who intercept or capture the email messages or the email communications over the network. However, an integrated email encryption system can also have some limitations or challenges, such as the compatibility, the usability, or the cost. Therefore, the recommended alternative to an integrated email encryption system is to encrypt sensitive data separately in attachments, which means that instead of encrypting the entire email message or the email communication, only the sensitive data or the information that is attached or appended to the email message or the email communication, such as the documents, the files, or the images, are encrypted or protected, using the cryptographic techniques or the mechanisms, such as the password, the passphrase, or the key. Encrypting sensitive data separately in attachments can provide a similar level of security or protection for the email messages or the email communications, as it can prevent or reduce the risk of unauthorized or inappropriate access, disclosure, modification, or spoofing of the sensitive data or the information by the third parties or the attackers who intercept or capture the email messages or the email communications over the network, and it can also overcome or address some of the limitations or challenges of the integrated email encryption system, such as the compatibility, the usability, or the cost. References: CISSP All-in-One Exam Guide, Eighth Edition, Chapter 4, page 116; Official (ISC)2 CISSP CBK Reference, Fifth Edition, Chapter 4, page 173