Server device, communication system, and computer-readable medium

A computer program product comprising a non-transitory computer-readable medium including programmed instructions, the instructions causing a computer included in a server device to execute:

• receiving a plurality of transmission data from a transmitting device;
• dividing the plurality of transmission data into first data and second data, the first data being a portion of the plurality of transmission data and the second data being an other portion of the plurality of transmission data;
• transmitting the first data to an external server device that delivers transmission data to a receiving device;
• storing, in a storage, the second data and metadata indicating that the second data is not transmitted to the external server device;
• receiving a transmission request for the second data from the receiving device or the external server device;
• transmitting the second data to the external server device in response to the transmission request;
• determining whether the second data is delivered to the receiving device by using the metadata;
• and
• performing deleting by prioritizing all or part of the second data delivered to the receiving device.

A server device comprising:

• one or more processors configured to:
• receive a plurality of transmission data from a transmitting device;
• divide the plurality of transmission data into first data and second data, the first data being a portion of the plurality of transmission data and the second data being an other portion of the plurality of transmission data;
• transmit the first data to an external server device that delivers transmission data to a receiving device;
• store, in a storage, the second data and metadata indicating that the second data is not transmitted to the external server device;
• receive a transmission request for the second data from the receiving device or the external server device;
• transmit the second data to the external server device in response to the transmission request;
• determine whether the second data is delivered to the receiving device by using the metadata;
• and
• perform deleting by prioritizing all or part of the second data delivered to the receiving device.