Full Date (Year, Month, Day), not just Time in Chat

I am not aware of any native way this can be achieved.
It should be possible via a plugin though so maybe you can find someone who is willing to do it for you.

Also please move this thread to the TeamSpeak 3 Client topic as you are not referring to the all new TeamSpeak Client.
I hate to write this all the time but as long as TeamSpeak refuses to call TeamSpeak 5 as it should be it will remain confusing af…