PURPOSE: To prevent electronic mails from omitting transmission by transmitting a not yet sent mail remaining in an electronic main file automatically.

CONSTITUTION: When a power supply at a sender side terminal equipment 1 is applied, a retrieval section 3 confirms whether or not a not yet sent mail exists in an electronic main file 5 via a terminal input and output control section 6. When any not yet sent mail exists, the electronic mail is extracted by a transmission section 4 via a terminal communication control section 7 and sent to a host computer 8. The host computer 8 sends the electronic mail to a designated receiver terminal equipment 9 and when the transmission of the electronic mail is finished, the status of the electronic mail is changed into the sent status. Thus, electronic mails not yet sent in error are prevented.