If you want to test to see if your image host will allow you to post images in the forum, change the query string on the end of the image URL.
The query string comes after the image filename in the URL. For example in this URL:
http://test.com/image.jpg?blah
the query string is "blah".
So if you had an image URL:
http://test.com/yourimg.jpg
when you post it in the forum type:
By changing the query string of the URL you will force your browser to reload the image, rather then using a cached copy of the image. That is the problem with posting images from other websites sometimes is that if they do not allow hot-linking, you may not be able to tell because you are viewing cached image, while the other forumers won't be able to see the image at all.
This can get a little tricky with image URLs from some image hosts. Sometimes there is already a query string in the URL. If this is the case then just add "&blah" to the end.
For example, if the URL is something like this:
http://test.com/gallery?id=1234
change it to this:
http://test.com/gallery?id=1234&blah
Now of course all these URL's I have been giving as examples should be enclosed in [img] tags when you make your post. This way you will be able to see if the image is loading up or not.
And be sure to PREVIEW your post first, no sence in posting if the images do not end up being visable.