Patent ID: 8732452

Claim:
A computer-implemented method for securely sending an email message from a first organization to a second organization over an unsecured network, the method comprising: receiving, by an email server of the first organization, an email message from a client computer of a sender associated with the first organization; identifying, by the email server of the first organization, an email server of a second organization associated with a recipient of the email message; sending, by the email server of the first organization, a request to a federation server configured to act as a trust broker between the first organization and the second organization, wherein the request identifies the email server of the first organization and requests a token for securely sending the email message to the email server of the second organization; receiving, by the email server of the first organization, a response to the request from the federation server, the response including a symmetric key and an encrypted token that contains the symmetric key, wherein the encrypted token can only be opened by the email server of the second organization with a private key of the second organization; and using, by the email server of the first organization, the symmetric key and the encrypted token received from the federation server to secure and send the email message to the email server of the second organization over the unsecured network.