You can bypass the the "Please enter a valid message." restriction pretty easily. All you have to do is use empty bbcode tags (Bold seems to reproduce it fairly easily). See the below post for an example.
There are a few other ways you can do similar things - 1x1 image, text the same as the background, etc. It's not possible to prevent, so it's more something that needs to be handled by active moderation.
There are a few other ways you can do similar things - 1x1 image, text the same as the background, etc. It's not possible to prevent, so it's more something that needs to be handled by active moderation.
Completely different beast @DBA, same with @Mike's examples.
You shouldn't be able to bypass the no content post restriction by using bbcode. Posting an image, or posting with the same bg contrast/colour font is completely different. Why is it different? There is actually content!
This is clearly a bug, there's nothing I can do besides making my own edits if the authors think otherwise.
I'd have thought it would be an easy enough check though. Just remove all the bbcode from the post, if the length of the remaining content is under the limit, then reject the post. In vB you could use pretty much the same trick to bypass the censor filter too.