Post by email is enabled for the Talk forum. This means you can post new topics by email.
You can see this example post:
The little email icon in the top right of the post shows that it was posted by email:
You can also reply to posts you get notified of by email, and the reply will get posted as a comment.
Each category has different email addresses. This meta category is meta@talk.tiddlywiki.org. Feel free to send it an email to experiment with.
The main #discussion category is post@talk.tiddlywiki.org, and is the only one that doesn’t follow the pattern of using the short name as the email address.