This certificate works on IE (Win7), Safari (Mac) and Firefox (Ubuntu), Android (LG Optimus) and iPhone (3GS) but no luck with WP7. Do I need to export it and import it to the phone or is there a Root Update I need to install?
Note: Nokia N8 wasn't happy with the certificate change either. I changed the certificate back and remote wiped both devices then swapped back to Geocert. Maybe it wants to do some upgrades via Zune before it's happy (N8 is currently updating so I have to wait until it's finished). Android and iPhone were fine with the change.
Solution: do not use the certificate generated for my server, instead, install the issuers certificate, i.e. RapidSSL CA. To do this, I the page on IE, viewed the Certification Path, select the issuer and view certificate, select details and Copy to file. Accept defaults and use the CER file created.
If you have a web server that can provide an alternative delivery mechanism to the phone as opposed to creating a hotmail account to email the certificate to yourself.
This mechanism also installed the certificate on the Nokia N8 successfully.
Answer: JasJar (WM5) does not support wildcard certificate. I thought it maybe the certificate chaining or CA itself, but connected it to the work exchange server, which has the same CA provider and chain, but has a named certificate, and it connected up fine.