A facsimile server connected to a mail server and a client over a network, and capable of sending and receiving an e-mail via the mail server. Certain data in a header of an e-mail to be sent to a recipient is used as identification data indicative of an origin of the e-mail. A controller identifies the origin of the e-mail based on the identification data upon receiving reception acknowledgement from the recipient. The facsimile server sends the reception acknowledgement to the client if it determines that the e-mail origin is the client. On the other hand, the facsimile server causes a printer to print the reception acknowledgement if it determines that the e-mail is originated from the facsimile server itself.