No, you as the sender cannot control how the file should be opened on the receiver's computer. Only by configuring the operating system can you define how a PDF file should be opened. You can try to create a ZIP archive with the file, this way, it is more likely that the file will be downloaded, but again, if a browser can open a ZIP'ed up PDF file, you cannot work around that.
The better solution would be to add logic to the PDF file that can determine if it's being opened in a non-Adobe PDF viewer, and then display a message that instructs the user to download the file and open it in Adobe Acrobat or Adobe Reader. You may also want to put these instructions into your email.
Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...
http://www.khkonsulting.com