Being that Outlook 2007 has limited HTML support and uses Word as a rendering engine, whereas other versions of Outlook use Internet Explorer to render email, adding a caption below the small gallery-style images that float on the left or right of your text causes an issue where the caption actually jumps above the text. The way to solve this is to simply include the caption as part of the image or to not use a caption for the small images. The large full-size image caption works fine.