Commands:

say say [Message] This command will make you say the specified message in chat.
say_team say_team [Message] This command will make you say the specified message in team chat.
cl_mute_all_but_friends_and_party cl_mute_all_but_friends_and_party [0 / 1] This command, if enabled (1), will mute communication from all players that aren't your friend on Steam, or in your party. Default is disabled (0).
cl_mute_enemy_team cl_mute_enemy_team [0 / 1] This command, if enabled (1), will mute communication from all enemy players. Default is disabled (0).