To provide a communications apparatus, capable of preventing wrong transmission due to the fact that an opposite-party communications apparatus allocated with an acquired IP address is replaced by an initial communications apparatus from the time of acquiring the IP address, by a DNS service to connection of the communications apparatus to the opposite-party communications apparatus.

The communications apparatus 1A is provided with a designation means of designating a mail address statically assigned to the opposite party communications apparatus; an IP address acquiring means for presenting the domain name of the mail address to acquire the IP address by making use of the DNS service; and a means of connecting to the communications apparatus assigned with the acquired IP address for receiving an SMTP response message, and transmitting an electronic mail to the connected communications apparatus, only if the information included in the response message agrees with the domain name being a predetermined portion of the mail address designated by the designating means.