mac mail not showing jpg attachments after yosemite install

I use Mac Mail and have recently upgraded to Yosemite.

Since upgrading I can no longer view jpg images sent by email from my security camera system. They used to be shown within the message, but since the upgrade to Yosemite they're not shown in the message anymore (well, they are shown in about 1% of messages), even the attachment won't open after saving to desktop.

When I try opening the attachment after I have saved it, it says it may be damaged or use a file format that Preview doesn't recognize.

I can view these images when using outlook on my mac, but preferred the Mail app, as it was easier to view the images in Mail.

Any suggestions on how to fix this?