"Sendmail" not working .

i used matlab 2012b to develop a code on sending a mail it works fine. but my friend uses the same code and run in matlab 2009a(7.8.0) it showing error

sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

i added the mail certification file to java i disabled the firewall i uninstall the anti visrus

but the problem remain showing the same error

Can anyone solve this Please...............