Mail is squashing / distorting certain jpg attachments

Searched around and have seen this question in some form, but no answer. I have more/new details from my own trouble shooting

Mail is sometimes squashing or distorting certain .JPG attachments when sent to others. Not all the time, just sometimes. The best way to describe it is it turns them into not quite accurate thumbnails. Re-saved as a JPEG-2000 in preview fixes it, but then if I convert back to .JPG, same issue.

Doesn't work if file name is converted to .JPEG.

Restarting mail and computer doesn't help.

Doesn't happen with ALL .JPG's, just some. For the ones it happens to, it happens each time.

Oddly enough, when the .JPG is attached with a Word file, no issues at all. Doesn't matter if it's an image I'm having issues with prior.

I do not believe it's a Mac or PC issue, as when I send it to my personal gmail account and access it there through Gmail's site, the image is distorted in the viewer and remains distorted when I open it up using preview.

Also while in Gmail, when you to to save the image, you have to right click it in the body of the text. The dropdown is now gone. Once you right click it, it prompts you to save it as 'unnamed.jpg.' wich is NOT what I'm sending.

Here's what I'm running:

OS 10.9.5

iMac Mid 2011

Mail 7.3

Mail is set to Plain Text for all messages.

Any thoughts?