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.