1. In a computer system comprising at least one memory to store processor-executable instructions and at least one processing unit communicatively coupled to the memory, a method for incorporating calendar functionality into an electronic message, the method comprising: receiving, from an organizer, a selection of a plurality of tentative time periods for a new calendar entry in the organizer's electronic calendar system; including, in an electronic message, a graphical representation of the tentative time periods selected by the organizer, wherein the graphical representation relies on remotely stored content reflecting the tentative time periods selected by the organizer that is not stored in the electronic message itself; sending the electronic message to at least one recipient; updating the remotely stored content to reflect changes to the tentative time periods.