Though mixed doubles are rarely broadcasted on Television, they are a part of official Tennis tournaments, including the Grand Slams. I am wondering, whether on that professional level, there is any unwritten Rules between the players.
Female players at average and at top-level have slower hitting speeds, which is especially important regarding serves. So even if they do not have slower reaction times, a women will simply not be used to returning a 220 kph serve (unless she is specializing on mixed doubles). So would a male server "restrain" himself when serving? Likewise, would a male player "attack" the female opponent standing at the net like he would with a male counterpart?