A method, server and system for the delivery of email messages with repetitive attachments. In one example embodiment, the method comprises determining a unique identifier for a content item that is referenced in an email message; determining, in dependence on the unique identifier, if an attachment corresponding to the content item is present in an attachment cache, and if a corresponding attachment is not present in the attachment cache then processing the content item to create the attachment and storing the attachment in the attachment cache identified by the unique identifier, and if the corresponding attachment is present in the attachment cache, then retrieving the corresponding attachment from the attachment cache; and sending the corresponding attachment to the mobile communications device.