A communication system and method transmits electronic mail among multiple users that are senders or recipients of the mail, or both. The system and method use and augment the Internet with a postal server and software (ePostal Service) linked to the Internet. The sender and recipient have terminals also linked to the Internet. The sender uses postal sender software to select transmission using the ePostal Service, with certain automatic premium services, and select certain optional premium services, typically available for an additional cost. The system and method include payment and accounting functions for use of the premium services. The system and method can operate with networks serving multiple terminals. Premium services include sender identification and certification, screening of mail for technical and content risks, encryption, confirmation of receipt and opening of the mail, customizable incentives for recipients to open received mail, and post office "window" and mail holding functions.