How do I use a GoDaddy wildcard cert on my email appliance?

Question

I have an email appliance with a self signed certificate. Everything has been running fine. But now I have customer who we cannot get emails from because their server rejects the self signed cert. I have a Wildcard SSL cert I purchased from Godaddy that I have used on a couple of Windows servers, but I am not sure in what format to download, since this is not a windows server. My options are: Apache, Exchange, IIS, Mac OS X, Tomcat, and other. I have read it needs a .pem format, but certs are something I don't usually go into and a little gun shy, so to speak. Or will I need to convert the cert to that format with a conversion tool. Any ideas would be appreciated.

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TRobinson · Answer

Don't know if you resolved this by now but I use godaddy cert with my appliance. I use the same UCC cert on my exchange farm as on the sophos appliance so I import to IIS on exchange and then export to pfx. I use openssl to carve it up into pieces and then copy and paste the text into a .pem that sophos needs. Here are my dirty notes I have:

Import into an IIS server 
 Export Cert with private key from IIS (PFX) 
 Using OpenSSL (readily available on many Linux distributions) run the following commands: 
 Export the private key file from the pfx file:
 
 openssl pkcs12 -in filename.pfx -nocerts -out key.pem

Export the certificate file from the pfx file:
 
 openssl pkcs12 -in filename.pfx -clcerts -nokeys -out cert.pem

Remove the passphrase from the private key ( guard this file as it is all an attacker needs to render your certificate useless ):
 
 openssl rsa -in key.pem -out server.key

Using a text editor, copy the information from the files created in step 3 and then 2 to create a .pem file. Make sure you save it using windows format from gedit if using linux. It should look like a huge perfect square and not one or two long contiguous lines of text. See format example below. 
 Import file on Sophos appliance and assign services to it. It will take a few minutes for the appliance to start using the new cert so be patient. .pem format example: 
 
 -----BEGIN RSA PRIVATE KEY----- private key -----END RSA PRIVATE KEY----- -----BEGIN CERTIFICATE----- the server certificate -----END CERTIFICATE----- 
 
 HTH