Allow for a custom message to explain why a user does not have permission to post.

I have a university-specific server for math classes that has gotten up to a respectable 150 users. We have a system where you can view class channels but can't post to them until you have the Student role, which you receive after you react to our rules. Pretty nifty. But I'm nervous that students won't read the welcome screen and will become confused as to why they can't post.

It would be nice if the placeholder message that reads "You do not have permission to send messages in this channel" was customizable. You could add an option next to the Post Messages permission, possibly one which appears once you disable the permission, or as a setting on the channel itself. (Just make sure the placeholder has a more distinguished color. At the moment it blends into the background.)

Alternatives: The message could be in a popup, or an ever-present toast, anything really. The setting could be attached to the roles, the channel, the permissions, or even server-wide in my case. It doesn't matter to me. It would have the most utility if it was attached to the specific permission settings for a specific role on a specific channel, but other options are viable in my case.