If double-click .pdf file icon in an email, file is supposed to open up in viewer like Adobe Acrobat Reader. If this does not take place for you, there are some possible solutions. You want to reset default program for .pdf viewing. You want to sever an old default association. Or you want to update edition of Adobe Acrobat Viewer.

Instructions

Step 1

Ensure that Adobe Acrobat Reader installed by attempting to open .pdf file stored on PC. Locate .pdf file, right click on it, and choose "Open." If file does not open, then search Windows Explorer for files with name "Adobe." If Acrobat Reader program does not appear in search, you want to download it. Ensure to download version for OS. If after installing Adobe Acrobat Reader, you can't open .pdf file from an email, try next step.

Step 2

Combine Adobe Acrobat Reader with .pdf files. The difficulty that Adobe Acrobat Reader is not default program for opening PDF files. Right tick .pdf file in email, choose "Save as," then save. Find file in Explorer right click on it, then choose "Open with." Search Adobe Acrobat Reader in file tree that appears and open it. Check option to remember your choice. This will combine .pdf files with Adobe Reader in future. If this does not solve problem, go to next step.

Step 3

Again install Adobe Acrobat Reader although you have it. Problem that version requires updating. E.g. version 5 of Acrobat can't open .pdf file save in version 9. Ensure to download version related to OS. If this does not solve problem, go to next step.

Step 4

Save .pdf attachment to drive and open it from there. If you can do this, and you have Vista and utilize Windows Mail.

Step 5

Attempt following if you have Firefox and obtaining message like "cannot be used to view PDF files in web browser." Close Firefox. Remove "nppdf32.dll" from 
"c:\program files\mozilla firefox\plugins." Look for file "nppdf." It will be in folder like "c:\program files\Adobe\Reader 8.0\Reader\Browser." Copy it to plugins folder where "nppdf32.dll" file was. Open Firefox again.