Issue with HTML Signature images in Mail 6.5

Hi,

Just wondering if anyone can help.
I hav created a HTML email signature in Mail 6.5, but when I send it out my logo image does not appear for some people or in Gmail.
While the fonts show perfectly using Inline CSS, I have tried everything to get the image working, but no luck.
The image is uploaded to a hosted server and the image url is fine.

Any suggestions are greatly appreciated.

cheers
Chris