Packet 0x81

Clients send Packet 0x81 to the server to send a simple mail to a recipient. The server sends it to clients to deliver the mail.

It seems that the game doesn't clear the entire message buffer before sending a message, so some random data (probably meaningless) ends up in the sent packet. Simple Mail packets can be shortened by the server (to remove excess garbage), and clients will still accept them.

Dreamcast Packet Format