OUTLOOK - SENDS .DAT FILES NOT .JPG OR .PDF FILES

[Steven Johnson]

I've been having problems with Outlook for a while and just reloaded the 365 Office suite on my Windows 10 computer.  Problem Statement:  When I try to add a .jpg or .pdf file to an email, the recipient receives a .dat file that is unreadable, not the .jpg or .pdf file.  

Is there a setting I can change in Outlook or something else I can do to fix this problem?  Or will I have to change my mail application to something other than Outlook.  

Thanks in advance for your help....   Steve

[#2]

Are those the infamous winmail.dat attachments? If so, follow the steps here: https://support.microsoft.com/en-us/help/2487954/how-to-specify-the-email-message-format-that-s-used...