Mail errors - Certificate issues

Mail errors - Certificate issues

I've put in emergency tickets, but I'm desperate for some answers ASAP.  I was getting the invalid SSL Certificate, so was able to get a couple of mailboxes back online by changing ports to 110. 

BUT, I can't send emails.  I'm getting:
Reason:sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

Somebody please help. We're at a standstill.


I'm almost ready to give up getting ANY help. Doing the trouble shooting myself and it would seem that the problem is that an SSL Certificate has been changed on my zoho account and I can no longer use my hostgator server as my smtp.  I CAN send via the Zoho smtp. That's not what I want to do.  What do I need to do to resolve this issue?