Twitch requests for exemption, confidentiality of letters?

Nowadays there are many videos where live streamers read their Twitch unbanning requests (which are actually sent privately and no one can see publicly) live in the stream and make fun of them, etc.

Why, out of interest, I wanted to ask whether it is legally forbidden to actually send these messages privately, to read them publicly and uncensored in the stream and to show them visually?

Spongy topic.

Courts have already ruled on this and the general consensus is that it is forbidden to publish private letters / emails. This violates personal rights.

It looks a little different with business emails, here it is forbidden even without the consent of the sender, but this is weakened by the public interest.

I strongly believe that such an "application" does not constitute private correspondence with the Youtuber. On the contrary, I even consider it a business correspondence, because the Youtuber is definitely an entrepreneur.

The only question left now is whether the rights of the sender outweigh the public interest. I took a quick look at what is shown with such requests for exemption, etc. And what content these "requests" ultimately have.
This is usually just silly chatter, insults or little jokes. So one can't say that the sender's interest is significantly high or that the consequences of a publication are so outweighed that the public interest is not weighted.

The public interest that I keep talking about here is simply that it might be fun for the audience. And when weighed against the consequences, humor prevails.