a method and system for user - customizable forms in an electronic mail system is provided . in preferred embodiments of the present invention , an electronic mail system provides for the receiving and displaying of mail information in conjunction with the use of a user - customizable form . the user provides a form data structure containing a description of the form fields and a form control procedure that implements the behavior of the fields . a transaction event processor is provided that invokes the form control procedure in response to the occurrence of events . the events include user entry of data . when the form control procedure completes the processing of the event , it returns to the transaction event processor . the electronic mail system provides the means for sending mail messages input through the use of a user - developed form .