Why am I not able to open an attached file in my mail on my Lumia 730 phone?

[Windows Central Question]

why i am not able to open attached file in my mail in my lumia 730 phone

First I open my mail id then I entered in inbox and I have a mail regarding my work.and I am not able to open that attached file.tell me how it happens.

 

[Pranshul Sood]

what is the file extension.? if it is a pdf file then u need to install a pdf reader like adobe reader