Well, I encountered almost exactly the opposite problem here last night. I was composing a long-ish post with photos (but no emojis) using the vanilla text-based editor on TRW, like I've done many times before. When I tried to preview it, or just outright post it, I hit the 403 wall. Then I tried putting the editor into wysiwyg mode, thinking it could not possibly help, and I could preview and post the entry just fine. During the time I was trying to post that entry, I was previewing and sending PM's in vanilla text mode just fine, so it wasn't a system-wide, time-local problem.
Go figure.
