Firefox 4 and screen capture

[i2ambler]

It looks like with firefox 4, you can paste screen captures into an email, then send it out. Interestingly - you cannot view the screen capture when trying to open in a zimbra account! Also - you CAN view the screen capture if you send to a yahoo account. If I look at the 'show original' in zimbra, I can see the mime encoded information. However, its not displaying. Yahoo - it displays. That seems weird.. any ideas?