Exchange 2010 CAS servers (accessed through TMG) and Comodo wild card certificate

Issue: following symptoms are noticed:

• ·         Outlook gets disconnected, autodiscover does not work from outside;
• ·         OWA works from outside;
• ·         Outlook works from inside.

Investigation TMG logs shows the failed connection attempts with Status: 0x80090325.  Also if you “Test” the firewall rule: it failed with certificate errors.

It’s happening for COMODO wildcard certificate

Solution:

Compare “Certificates” mmc for working CAS server and not working CAS server.

Notice the “working” CAS server has many COMODO certificates in the various folders in Certificates console, while “not working” CAS server has none.

1. Export from the working CAS server, import to not working CAS server.
2. Re-assign Exchange Certificate (click on “Server Configuration” in EMC).