XOmail/Guard is a family of secure messaging Guard/Gateway applications. The most important being the TCSEC B1+ certified COTS Mail Guard used by NATO since 1997. It is built around the old Multi-Level Secure Unix System V/MLS and the Thales messaging product.

The Thales Mail Guard has been a key component in all NATO led operations (SFOR, KFOR, ISAF, etc.) allowing controlled flow of information between NATO members and collaborating non-NATO members. It is therefore not only an MLS-certified, but also a proven product that also has been used by some nations for their own services.

The development of the product takes place in Thales' facilities in Trondheim, Norway. The team has 20 years of experience with certified Multi-Level Secure military messaging.