Patent ID: 8341399

Claim:
A method of retrieving certificates associated with senders of digitally signed electronic mail messages received at a user's mobile computing device, wherein the method is performed by an application executing on the user's mobile computing device, the method comprising: after an electronic mail message comprising a digital signature of a sender arrives at the user's mobile computing device, before the electronic mail message is user-selected for opening, and before verifying the digital signature: identifying a certificate associated with the sender that comprises a public key capable of verifying the digital signature, wherein the certificate is not included in the electronic mail message; and determining whether the certificate is stored in a certificate store on the user's mobile computing device; retrieving the certificate from a certificate store remotely located from the user's mobile computing device if the certificate is determined to be not stored on the user's mobile computing device; verifying, by the user's mobile computing device, the digital signature of the electronic mail message using the certificate; and generating an indicator for display at the user's mobile computing device that indicates whether the digital signature is successfully verified.