Will this program help me to e-mail a pdf file from my thumb drive?

NULL

Of course, if you set eM Client as default application then you should be able to send the pdf file without any problems.

pdf files do not open

Hi, can you give us a bit more information on this issue? Are you seeing any errors? What version of eM Client are you currently using?
What mail service are you using? Can you make a screenshot of the issue?

Thank you,
Paul.