And let me just put this here before people start exaggerating (aka lying) to try and make it seem like the game is unplayable while muted:
|You Cannot|
- Reply to Whispers from WoW Friends/Non-friends
- Talk in global channels (General, Trade, etc.) or Instance Chats (Raid, Party, Battlegrounds)
- Create Calendar Invites/Events
- Send in-game mail, party invitations to Non-friends, or War Game and Duel invitations
- Create a new listing or update a listing for a pre-made Group listing
- Speak in Blizzard Chat (including communities and Real ID
|You Can|
- See Whispers from WoW Friends/Non-friends
- Party/Raid Chat (with Invited friends)
- Talk in Global Channels that have a moderator
- Share Quests
- Sign up for a pre-made group
- Use Guild Chat
From: https://us.battle.net/support/en/article/44277
So yeah, enjoy your raids, guild chat, quest sharing and all that, even while muted. This is surgically designed to kick trolling and spammers in the nuts and they know it.