I don't know of any converters for this as the file can just be saved as a jpg in the programme that made it. Can the sender not re-save the pic as a Jpg?
In Photodeluxe, you have to use the 'file, export file type' to save as .jpg. Photodeluxe files can also be read by Adobe photoshop, photoshop elements. Do you know anyone with these programmes who can re-save them as .jpgs?
I would be glad to do it for you as I have the programme if you want to e-mail them, but I understand the pics may be personal to you.
Your best bet is to find someone with anyone of the 3 programmes mentioned above to save them in a different format. Unless anyone has other ideas.