Before you open any attachments you should first be sure you trust the sender. To help you please add some information. What is your operating system and what extension does the attachment have, the three letters after the dot on its name?

I trust the sender

I think HP is the operating system

the three letters after the dot on its name means nothing to me.   When I open the page there is only the normal things i.e. subject, from, to, date, priority.  The only indication that there is an attachment is the paperclip after the size at the very beginning.  When the page is opened The page itself is blank.  Trustnet is the company I use for all emails,

By operating system I meant Windows, Linux, Mac, etc.. I refuse to use Windows so I've been with Linux forever. As to opening attachments, maybe whoever sent you this - sent one with no content. Do you have more than one account on TBird? If so, send yourself an email and attach a .png or .txt file and see what happens. I just did that and the .png file (a graphic) opened up within the email automatically.

I tried this again using a text file as the attachment and got this screen.