A method at a wireless mail server, the method comprising: receiving, from a sender, a new message; appending an original message to said new message to form a composite message; storing, in memory, expected receipt content, said expected receipt content generated based on said composite message; transmitting, to a recipient, said composite message; receiving a receipt message from a recipient; determining that the receipt message includes a signed receipt generated responsive to a receipt request transmitted in conjunction with an earlier transmission of a composite message on behalf of a mobile communication device; upon determining that the message includes a signed receipt, the wireless mail server extracting, from the receipt message, a receipt and a receipt signature; obtaining, from said memory information for validating the receipt; upon obtaining the information for validating the receipt, the wireless mail server attempting to validate the receipt by matching values of specific receipt attributes with specific corresponding values in the information for validating the receipt, thereby generating a validation result; upon determining that the receipt has been validated, amending a validation result to indicate that the receipt has been validated; attempting to verify the receipt signature; upon determining that the receipt signature has been verified, amending the validation result to indicate that the receipt signature has been verified; transmitting the validation result to a mobile communication device along with the receipt message including the signed receipt; extracting the information for validating the receipt from a saved copy of the composite message; and locating the information for validating the receipt, in a cache on the wireless mail server, where the wireless mail server has stored the information associated with the saved copy of the composite message. receiving, from a sender, a new message; appending an original message to said new message to form a composite message; storing, in memory, expected receipt content, said expected receipt content generated based on said composite message; transmitting, to a recipient, said composite message; receiving a receipt message from a recipient; determining that the receipt message includes a signed receipt generated responsive to a receipt request transmitted in conjunction with an earlier transmission of a composite message on behalf of a mobile communication device; upon determining that the message includes a signed receipt, the wireless mail server extracting, from the receipt message, a receipt and a receipt signature; obtaining, from said memory information for validating the receipt; upon obtaining the information for validating the receipt, the wireless mail server attempting to validate the receipt by matching values of specific receipt attributes with specific corresponding values in the information for validating the receipt, thereby generating a validation result; upon determining that the receipt has been validated, amending a validation result to indicate that the receipt has been validated; attempting to verify the receipt signature; upon determining that the receipt signature has been verified, amending the validation result to indicate that the receipt signature has been verified; transmitting the validation result to a mobile communication device along with the receipt message including the signed receipt; extracting the information for validating the receipt from a saved copy of the composite message; and locating the information for validating the receipt, in a cache on the wireless mail server, where the wireless mail server has stored the information associated with the saved copy of the composite message.