A method is provided to handle an electronic mail message such that the receiver of the e-mail message can verify the integrity of the message. A request is provided from a sender's side to a service. The request includes information regarding the e-mail message. The service processes at least a portion of the request to generate a result. For example, the service may encrypt the portion of the request, according to a public/private key encryption scheme, to generate a digital signature as the result. The service provides the result to the sender's side. At the sender's side, the result is incorporated into the e-mail message and the result-incorporated message is transmitted via an e-mail system. At the receiver's side, the result-incorporated e-mail message is processed to assess the integrity of the received e-mail message.