MessageLabs has produced a new encryption service to protect e-mail sent between business partners.

The Boundary Encryption Service is designed to help companies protect themselves against hackers and comply with new data privacy and integrity laws, including Sarbanes-Oxley and Gramm-Leach-Bliley.

MessageLabs customers that want to use the service designate an e-mail domain that will be used to send the encrypted e-mail, and provide the domains of trusted partners who will engage in secure e-mail exchanges. MessageLabs' servers ensure that e-mail sent to and from the designated domains is secured using TLS (Transport Layer Security) encryption. E-mail traffic to all other domains is sent "in the clear" using just SMTP (Simple Mail Transfer Protocol), the company said.

The Boundary Encryption Service creates a secure private e-mail network between designated domains, but doesn't rely on desktop tools or individual e-mail correspondents to encrypt traffic, the company said. Also, e-mail is only encrypted when it passes outside the company network, but remains unencrypted otherwise, which helps e-mail storage and archiving, in adherence with other provisions of new data integrity regulations, MessageLabs said.

Security experts agree that broader use of encryption would curtail problems like e-mail worms, viruses and phishing identity theft attacks, which take advantage of shortcomings in the SMTP protocol.

A number of e-mail encryption technologies exist to secure SMTP traffic, including S/MIME (Secure Multipurpose Internet Mail Extensions), which uses public-key technology to send secure, encrypted e-mail between individual correspondents.

SMTP over TLS, which is used in the Boundary Encryption Service, allows organisations to secure communications among the thousands of e-mail servers on the Internet, rather than among the millions of e-mail users, which S/MIME requires, and is considered easier and less expensive to manage, MessageLabs said.

The Boundary Encryption Service is available immediately. The service list price is $3 per user per month, in addition to a $700 flat fee to configure Boundary Encryption Service partner end points, but discounts are available depending on the size of the installation, length of the service contract and other factors, a company spokeswoman said.