SSL certificates per domain

SSL Certificates per domain

   KB 15103        Last updated on 07/11/2015  

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This document explains how to add per domain cert on a ZCS server.

Note: This feature will not enable domain certificate for smtps connections. RFE #50127

Until ZCS 6.x, per domain ssl certificate or multiple ssl certificates on a single ZCS was not supported. RFE #8128. This feature has been introduced in ZCS 7.x.

In this example, I am adding a new domain called and deploying a new certificate for

Note: When ZCS-9.x is released, there's no need to configure zimbraVirtualIPAddress per domain anymore. RFE #56178


  • Zimbra proxy service must be installed and enabled on the server. In multi server environment, do these steps on the proxy node.
  • You should have a signed certificate + matching key pair and the trusted chain certs from your CA (Certificate Authority) .
  • You will need to add ipv4 addresses per domain which will pair to the respective domain name. For example: => => =>

Configuring IP address and domain

1. Add a new ipv4 address to the server which will pair to name (via the example virtual hostname You can do it using IP address aliasing. For example, the new address can be assigned to eth0:1 device. Lets consider the new ipv4 address is which should be an A record for The IP address could be public (if server is on Internet) or internal (if the server is behind firewall/NAT'ed).

2. Add the new domain Set zimbraVirtualHostName to and zimbraVirtualIPAddress to Make sure the zimbraVirtualHostName is set to the name which will be used to access the domain (URL) and the SSL certificate is signed for same name.

 zmprov cd zimbraVirtualHostName "" zimbraVirtualIPAddress ""

NOTE: If the server is behind firewall and NAT'ed with external address, make sure the external requests for "" hits the aliased IP address and not the actual local IP of server.

Verifying and Preparing the Certificates

We have three files received from the CA. The server (domain) certificate, two chain certs. And we have existing key file (which was used to generate the csr)

1. Save the certificate, key and chain files to a directory /tmp/ You can receive single or multiple chain certs from your CA. Here we have two chain certs from the CA. i.e. and

 ls /tmp/

2. Add the chain certs to a single file called example.com_ca.crt

 cat >> example.com_ca.crt

3. Confirm if the key and certificate matches and chain certs completes the trust.

 /opt/zimbra/bin/zmcertmgr verifycrt comm /tmp/ /tmp/ /tmp/
  • Check the output, it should say something like this. If not, make sure you have correct key and chain cert files.
 ** Verifying against
 Certificate ( and private key ( match.
 Valid Certificate: OK

Deploying the Certificate on domain

1. Add the domain certificate and chain files to a single file called

 cat example.com_ca.crt >>

2. Run following to save the certificates and key in ldap database.

 /opt/zimbra/libexec/zmdomaincertmgr savecrt
  • The syntax is:
 /opt/zimbra/libexec/zmdomaincertmgr savecrt <domainname> <certificate with chain certs> <keyfile>

3. Run following to deploy the domain certificate. This will save the certificate and key as /opt/zimbra/conf/domaincerts/

 /opt/zimbra/libexec/zmdomaincertmgr deploycrts

4. Make sure the is resolving to its local IP address from Zimbra host. Or make an similar entry in /etc/hosts file.

Proxy Check

Run these commands on proxy hosts.

  • zimbraReverseProxyGenConfigPerVirtualHostname should be set to TRUE in server and global config.
 zmprov gs `zmhostname` zimbraReverseProxyGenConfigPerVirtualHostname
 zmprov gacf zimbraReverseProxyGenConfigPerVirtualHostname

Use these command to set it to TRUE.

 zmprov ms `zmhostname` zimbraReverseProxyGenConfigPerVirtualHostname TRUE
 zmprov mcf zimbraReverseProxyGenConfigPerVirtualHostname TRUE

Re-write and restart Proxy

  • Restart the proxy to re-write the changes to proxy config
 zmproxyctl restart
  • Once the restart is successfull, try to access the domain using the URL which is set in "zimbraVirtualHostName" over https. And check the certificate loaded in the browser. In this case the URL will be


Run this command locally on zimbra server to check if the correct domain cert is offered while accessing the domain with "zimbraVirtualHostName" or "zimbraVirtualIPAddress"

 openssl s_client -connect
 openssl s_client -connect


  • If you do not see domain cert by accessing the domain with its zimbraVirtualHostName ( Make sure the https connection from Internet/intranet is going to server's local IP address which is defined in zimbraVirtualIPAddress.
  • If the proxy startup gives following error, try to change the order of certificates in /opt/zimbra/conf/domaincerts/ file and restart proxy.
 Starting nginx...nginx: [emerg] SSL_CTX_use_PrivateKey_file("/opt/zimbra/conf/domaincerts/") failed (SSL: error:0B080074:x509 certificate 
 routines:X509_check_private_key:key values mismatch)
  • If you are using multiple proxy servers or adding new proxy servers, make sure you copy all the contents of /opt/zimbra/conf/domaincerts/ among all proxy servers. Otherwise proxy service will fail to start.

Verified Against: ZCS 7.0 Date Created: 01/15/2014
Article ID: Date Modified: 07/11/2015

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