1. A method implemented by a computing system in response to execution of program code by a processor of the computing system, the method comprising: creating, by a device operated by a first party, a business document, the business document comprising an instance of a software model representing a real world entity involved in a business transaction; generating a markup language representation of the business document based on a business object model implemented by a business application platform; generating a first multi-part Multipurpose Internet Mail Extension (MIME) electronic mail message comprising a first part and a second part, the first part associated with a text content-type and the second part associated with an attachment content-disposition, and the second part comprising the markup language representation of the business document; transmitting the first electronic mail message to: (i) a device associated with a second party and (ii) the business application platform associated with the business document and implementing the business object model, wherein the business application platform is to extract the markup language representation of the business document, instantiate a business object instance of the business document based on the markup language representation of the business document, and store the business object instance instantiated based on the markup language representation of the business document; receiving, by a device, a request for a modification to the business document; editing, by a device, the business document; generating a second markup language representation of the edited business document based on the business object model; generating a second multi-part MIME electronic mail message comprising a third part, a fourth part, a second Content-ID identifying a sender of the second multi-part MIME electronic mail message, the filename of the business document and a second timestamp, the third part associated with the text content-type and the fourth part associated with the attachment content-disposition, and the fourth part comprising the second markup language representation; transmitting the second electronic mail message to: (i) a device associated with a third party and (ii) the business application platform, wherein the business application platform is to edit a business object instance of the business document based on the second markup language representation; and receiving, from the business application platform, verification that the third party has approved the business document.