Embedded .jpg images can't be viewed by recipients

[yahu855]

When I compose a message in Roundcube using HTML and attach or embed a photo (.jpg), the recipients only see a gray box. The image is not available for them to view. I've tried to change settings, but nothing seems to fix. How do I make images viewable by recipients? I'm using Roundcube, Firefox v. 5.0.1 on a Mac Pro OS X 10.6.8

Thanks