1. A computer implemented method for integrating services in a calendar application comprising: specifying an event within an electronic calendar of a calendar application, the calendar application being operable to send and receive e-mails, wherein the event is being taken from the group consisting of singular events and recurring events, the recurring events being events with a certain recurrence pattern, the events being data objects in an electronic calendar of the calendar application; submitting a service request to a service, the service request comprising the specification of the event, the service request being sent in the form of an e-mail to a service e-mail address by the calendar application, wherein the service e-mail address represents the service, and wherein the e-mail is a meeting request e-mail; receiving the service request sent to the service e-mail address of the service being represented by the service e-mail address; executing the service after the delivery of the service request e-mail to the service e-mail address of the service; returning an update request by the service, the update request comprising a result generated by the requested service, the update request being an e-mail sent to the e-mail address used by the calendar application for sending the service request, the update request e-mail being a meeting request response e-mail or a second meeting request e-mail; receiving the update request from the requested service by the calendar application; and executing the received update request by the calendar application, resulting in an automatic update of the electronic calendar of the calendar application.