Processing of messages to be transmitted over communication networks

A method for processing messages to be transferred from a transmitting entity to a receiving entity over a communication network, the method comprising the steps of:

• at the transmitting entity
• obtaining from a sender's email client a multipart message containing text and attachments, addressed to a recipient;
• defining a substantially unique identifier for an attachment;
• comparing the substantially unique identifier to the identifiers previously stored in a memory,
• concluding that the attachment has not been previously transferred to the receiving entity when the substantially unique identifier is missing in the identifiers stored,
• selecting a base attachment with the related identifier which are known to be available for the receiving entity,
• calculating a difference between the attachment and the base attachment,
• replacing said attachment with said base attachment-related identifier and the difference, and;
• forwarding the message for transfer to the receiving entity,
• at the receiving entity
• responsive to the message with said substantially identifier and the difference being attached thereto:
• retrieving from a memory the base attachment on the basis of said base attachment-related identifier,
• creating the attachment by combining said difference with the base attachment
• reconstructing the original multipart message by replacing the identifier and the difference with the attachment to the message received,
• sending the reconstructed original multipart message to the recipient.