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This article applies to the following ZCS versions.
ZCS 5.0

Use the following instructions to import and install a Thawte SSL Certificate (in SSL123 format) on a ZCS 5.0.x server.

1. Generate the CSR from admin console and get it signed by Thawte in .pem format.

2. Save the cert in /opt/zimbra/ssl/zimbra/commercial and rename it to commercial.crt. This directory should also contain commercial.key, which was generated at the time of CSR creation.

3. Download ThawteServerCA_b64.txt and save it at /opt/zimbra/ssl/zimbra/commercial.

4. Run following commands as root:

cd /opt/zimbra/ssl/zimbra/commercial/
/opt/zimbra/bin/zmcertmgr verifycrt comm commercial.key commercial.crt ThawteServerCA_b64.txt

5. If output of above commands looks good, proceed to install the certificate.

/opt/zimbra/bin/zmcertmgr deploycrt comm commercial.crt ThawteServerCA_b64.txt

6. Restart the Zimbra services.

su - zimbra
zmcontrol stop
zmcontrol start

7. Verify that the Web interface is loading correctly with the new certificate.