Encrypted email can provide the capability to encrypt the body and attachments of emails. For example, OpenPGP and S-MIME standards are widely used encryption methods which have been implemented by a range of free and commercial software products.
The sending and receiving of encrypted email requires the use of compatible email client software and requires configuration in advance. A wide range of free and proprietary products are available for desktop, laptop and mobile operating systems. There are some specialist webmail providers which support encrypted email but it is not generally supported by the majority of online email providers, although there are some browser plug-ins which can provide this capability and progress is being made in this area.
Encrypted email uses asymmetric encryption and requires a user to generate a key pair before they will be able to send an encrypted email. Users will also have to exchange public keys before an encrypted email can be sent between them. The private key must be kept secret.
Configuring encrypted email within a corporate environment can cause complications for server-based malware scanning products as the content and attachments will be encrypted and may even be actively blocked by the scanning software. There can also be compatibility issues with automated email processing systems or managing multiple private keys amongst multiple staff (eg a common mailbox at email@example.com).
It can also be difficult for some individuals to install compatible software, generate key pairs, and appreciate the necessity of key management. Furthermore, loss of the private key can mean that received emails that were encrypted with the associated public key cannot be decrypted.
It is therefore necessary to consider the risks and investment required and whether there are alternative solutions for encrypted transfer of data should be considered.
Data controllers should have a policy governing encrypted email, including guidelines that enable staff to understand when they should or should not use it. For example, there may be a guideline stating that any email containing sensitive personal data (either in the body or as an unencrypted attachment) should be sent encrypted.