Outlook displaying wrong remote image

Hi, i'm running Lion 10.7.5 on iMac.

Recently we changed an image we host on our site; our system (remotely) attach this image to all emails it generates.

Now when in Ms Outlook i open an email i can still see the old image and not the new one we are actually hosting.

Same thing happens using Mail.

If i right click on the image and open in Safari the correct image pops up.

I tried deleting the cache booting in safe mode but didn't work.

Can you help?

Thanx