PDF submissions received through notification is previewed as text

When the forms come in and pdf are attached, when we go to open it it opens it as a text instead of through preview. It just started today. It tells us that it does not know if it is ok for preview to open it. We are still looking to see if it is an issue on our end, but wanted to check with you guys. Do you know why all of a sudden it would do it only when the pdf comes through jotform.

It opens any other pdf with no issues. It is only when they are attached through jotform.

It is also doing it with jpg

I have tested the PDF submission received in a notification and see that the PDF file is previewed normally. Do you mean to say that the PDF file previewed in the email is not displaying correctly? Could you check by using a different browser to check if it is causing by the browser? How is the file displayed when it is downloaded to your PC? 

Could you try creating a new notification and enable the PDF attachment to see if that works normally? Please get back to us if the issue still persists. We will be happy to assist you further.