So up until recently gmail was using Thawte signed certificates. Turns out that has changed and so the instructions i found on the net didn't quite work to keep sending out email.
Example on how to get it working with Thawte certs
the only thing you have to change is get the certificate for Equifax Secure Certificate Authority. I found one here at geotrust.
wget https://www.geotrust.com/resources/root_certificates/certificates/Equifax_Secure_Certificate_Authority.cer --no-check-certificate