I'm receiving the following when I try to send email.  I realize it must have something to do with the certificate of the domain I'm sending to but I don't know how to fix it.  I'm trying to send to a coworker and I have my pop account set up in zoho.

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

Any help would be appreciated.

Renda