JPG garbled in OSX10.8 but viewable on iPhone?

I am receiving a jpg from an IP camera by email and it is happily viewable on my iPhone but completely garbled when I either open it within OSX Mail or save the attachment and then try opening it using any other application.

Here is a typical 'result'


any ideas? Seems strange that whetever format or variation of the jpg standard that is being used it is OK on an iphone but not on a Macbook!