An important note:
If you use an image stored on an image hosting service you must use a direct URLfor the image, not embed codes.
You can not currently use an image with a .jpeg extension because the forum software does not recognise the 4 letter extension even though the image format is the same as .jpg.
Your image must be .JPG, .PNG, or .GIF and cannot exceed 100x100 pixels.
Sorry but those two highlighted statements are not strictly true. Using the free Imgur account at least, the embed code can be pasted directly into a TM post as the image tags are conveniently already present. You simply copy the BBCode link as shown below, similar to tm-img.
![[Linked Image]](http://i.imgur.com/VhjjOc5.png)
No issues with .jpg image suffix being changed to .jpeg either which causes issues on TM for avatar links. On that subject whilst there is a warning to limit image size to 100 x 100 pixels exclusively for avatar image use, in practice there is no such limit, not to say discretion on picture size shouldn't be used.