This guide will show you how to easily secure your Zimbra Mail Server with Let’s Encrypt SSL certificate. The default installation of Zimbra generates self-signed SSL certificate for Mails services – POP3/IMAP/SMTP over TLS and for HTTPS access to Zimbra console services.

A self-signed certificate can be used for test deployments but for Production setups I recommend you get a commercial certificate to give your business credibility and better security. If you don’t have a budget for established CA certificate you can use free Let’s Encrypt Certificate to secure your Zimbra server.

Let’s Encrypt is a free, automated, and open certificate authority brought to you by the nonprofit Internet Security Research Group (ISRG). The process of certificate generation is automated and fit for Developers. Before you follow this guide along ensure you have a running Zimbra server. Below guides can help you.

Install Zimbra Server on RHEL 8 | CentOS 8

Install Zimbra Server on Ubuntu

Step 1: Install certbot-auto tool

We’ll use the certbot-auto tool to request for Let’s Encrypt SSL Certificates. The tools is not installed by default on your system but can easily be downloaded and installed. The certbot-auto wrapper script installs Certbot, obtaining some dependencies from your web server OS and putting others in a python virtual environment.

wget https://dl.eff.org/certbot-auto

make the script executable.

chmod  x certbot-auto

Move the script to directory in your PATH.

sudo mv certbot-auto /usr/local/bin

Confirm it working.

$ sudo certbot-auto --version
certbot 1.5.0

If you get prompt to install dependencies accept it.

Step 2: Stop Zimbra Proxy Service

We need to stop the jetty or nginx service services before we can configure it to use Let’s Encrypt SSL certificate.

$ sudo su - zimbra -c "zmproxyctl stop"
Stopping proxy...done.

$ sudo su - zimbra -c "zmmailboxdctl stop"
Stopping mailboxd...done.

Step 3: Obtain Let’s Encrypt SSL Certificate

Once the Zimbra proxy and mailboxd services are stopped we can proceed to request for Let’s Encrypt in auto mode. Make sure you pass all the hostnames used by your Mail Server. 

# export EMAIL="[email protected]"
# certbot-auto certonly --standalone 
  -d mail.computingforgeeks.com 
  --preferred-challenges http 
  --agree-tos 
  -n 
  -m $EMAIL 
  --keep-until-expiring

When you run the commands you’ll see output like below.

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator standalone, Installer None
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for mail.computingforgeeks.com
Waiting for verification...
Cleaning up challenges

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/mail.computingforgeeks.com/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/mail.computingforgeeks.com/privkey.pem
   Your cert will expire on 2020-10-03. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot-auto
   again. To non-interactively renew *all* of your certificates, run
   "certbot-auto renew"
 - Your account credentials have been saved in your Certbot
   configuration directory at /etc/letsencrypt. You should make a
   secure backup of this folder now. This configuration directory will
   also contain certificates and private keys obtained by Certbot so
   making regular backups of this folder is ideal.
 - If you like Certbot, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le

You can find all your files under /etc/letsencrypt/live/$domain

$ ls -lh /etc/letsencrypt/live/mail.computingforgeeks.com
total 4.0K
lrwxrwxrwx. 1 root root  50 Jul  5 23:42 cert.pem -> ../../archive/mail.computingforgeeks.com/cert1.pem
lrwxrwxrwx. 1 root root  51 Jul  5 23:42 chain.pem -> ../../archive/mail.computingforgeeks.com/chain1.pem
lrwxrwxrwx. 1 root root  55 Jul  5 23:42 fullchain.pem -> ../../archive/mail.computingforgeeks.com/fullchain1.pem
lrwxrwxrwx. 1 root root  53 Jul  5 23:42 privkey.pem -> ../../archive/mail.computingforgeeks.com/privkey1.pem
-rw-r--r--. 1 root root 692 Jul  5 23:42 README

You’ll see a number of files.

  • cert.pem: The actual certificate file
  • chain.pem: The chain file
  • fullchain.pem: Concatenation of cert.pem chain.pem
  • privkey.pem: Private key

Step 4: Secure Zimbra Mail Server with Let’s Encrypt SSL Certificate

Create directory that will hold Let’s Encrypt certificates for Zimbra Server.

sudo mkdir /opt/zimbra/ssl/letsencrypt

Copy Certificate files.

CERTPATH=/etc/letsencrypt/live/mail.computingforgeeks.com
sudo cp  $CERTPATH/* /opt/zimbra/ssl/letsencrypt/

Confirm files are copied successfully.

$ ls /opt/zimbra/ssl/letsencrypt/
cert.pem  chain.pem  fullchain.pem  privkey.pem  README

We now need to build a proper Intermediate CA plus Root CA. You must to use the IdenTrust root Certificate and merge it after the chain.pem.

cat $CERTPATH/chain.pem | sudo tee /opt/zimbra/ssl/letsencrypt/zimbra_chain.pem

View the file contents:

$ cat /opt/zimbra/ssl/letsencrypt/zimbra_chain.pem
-----BEGIN CERTIFICATE-----
MIIEkjCCA3qgAwIBAgIQCgFBQgAAAVOFc2oLheynCDANBgkqhkiG9w0BAQsFADA/
MSQwIgYDVQQKExtEaWdpdGFsIFNpZ25hdHVyZSBUcnVzdCBDby4xFzAVBgNVBAMT
DkRTVCBSb290IENBIFgzMB4XDTE2MDMxNzE2NDA0NloXDTIxMDMxNzE2NDA0Nlow
SjELMAkGA1UEBhMCVVMxFjAUBgNVBAoTDUxldCdzIEVuY3J5cHQxIzAhBgNVBAMT
GkxldCdzIEVuY3J5cHQgQXV0aG9yaXR5IFgzMIIBIjANBgkqhkiG9w0BAQEFAAOC
AQ8AMIIBCgKCAQEAnNMM8FrlLke3cl03g7NoYzDq1zUmGSXhvb418XCSL7e4S0EF
q6meNQhY7LEqxGiHC6PjdeTm86dicbp5gWAf15Gan/PQeGdxyGkOlZHP/uaZ6WA8
SMx yk13EiSdRxta67nsHjcAHJyse6cF6s5K671B5TaYucv9bTyWaN8jKkKQDIZ0
Z8h/pZq4UmEUEz9l6YKHy9v6Dlb2honzhT Xhq w3Brvaw2VFn3EK6BlspkENnWA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 dla5cEilaUcne8IkCJLxWh9KEik3JHRRHGJo
uM2VcGfl96S8TihRzZvoroed6ti6WqEBmtzw3Wodatg VyOeph4EYpr/1wXKtx8/
wApIvJSwtmVi4MFU5aMqrSDE6ea73Mj2tcMyo5jMd6jmeWUHK8so/joWUoHOUgwu
X4Po1QYz 3dszkDqMp4fklxBwXRsW10KXzPMTZ sOPAveyxindmjkW8lGy QsRlG
PfZ G6Z6h7mjem0Y iWlkYcV4PIWL1iwBi8saCbGS5jN2p8M X Q7UNKEkROb3N6
KOqkqm57TH2H3eDJAkSnh6/DNFu0Qg==
-----END CERTIFICATE-----

Combine the chain.pem with the root CA – Order is chain before the root CA.

sudo tee -a /opt/zimbra/ssl/letsencrypt/zimbra_chain.pem<<EOF
-----BEGIN CERTIFICATE-----
MIIDSjCCAjKgAwIBAgIQRK wgNajJ7qJMDmGLvhAazANBgkqhkiG9w0BAQUFADA/
MSQwIgYDVQQKExtEaWdpdGFsIFNpZ25hdHVyZSBUcnVzdCBDby4xFzAVBgNVBAMT
DkRTVCBSb290IENBIFgzMB4XDTAwMDkzMDIxMTIxOVoXDTIxMDkzMDE0MDExNVow
PzEkMCIGA1UEChMbRGlnaXRhbCBTaWduYXR1cmUgVHJ1c3QgQ28uMRcwFQYDVQQD
Ew5EU1QgUm9vdCBDQSBYMzCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEB
AN v6ZdQCINXtMxiZfaQguzH0yxrMMpb7NnDfcdAwRgUi DoM3ZJKuM/IUmTrE4O
rz5Iy2Xu/NMhD2XSKtkyj4zl93ewEnu1lcCJo6m67XMuegwGMoOifooUMM0RoOEq
OLl5CjH9UL2AZd 3UWODyOKIYepLYYHsUmu5ouJLGiifSKOeDNoJjj4XLh7dIN9b
xiqKqy69cK3FCxolkHRyxXtqqzTWMIn/5WgTe1QLyNau7Fqckh49ZLOMxt /yUFw
7BZy1SbsOFU5Q9D8/RhcQPGX69Wam40dutolucbY38EVAjqr2m7xPi71XAicPNaD
aeQQmxkqtilX4 U9m5/wAl0CAwEAAaNCMEAwDwYDVR0TAQH/BAUwAwEB/zAOBgNV
HQ8BAf8EBAMCAQYwHQYDVR0OBBYEFMSnsaR7LHH62 FLkHX/xBVghYkQMA0GCSqG
SIb3DQEBBQUAA4IBAQCjGiybFwBcqR7uKGY3Or Dxz9LwwmglSBd49lZRNI DT69
ikugdB/OEIKcdBodfpga3csTS7MgROSR6cz8faXbauX 5v3gTt23ADq1cEmv8uXr
AvHRAosZy5Q6XkjEGB5YGV8eAlrwDPGxrancWYaLbumR9YbK rlmM6pZW87ipxZz
R8srzJmwN0jP41ZL9c8PDHIyh8bwRLtTcm1D9SZImlJnt1ir/md2cXjbDaJWFBM5
JDGFoqgCWjBH4d1QB7wCCZAA62RjYJsWvIjJEubSfZGL T0yjWW06XyxV3bqxbYo
Ob8VZRzI9neWagqNdwvYkQsEjgfbKbYK7p2CNTUQ
-----END CERTIFICATE-----
EOF

Confirm the resulting file has the two certificates.

$ cat /opt/zimbra/ssl/letsencrypt/zimbra_chain.pem
-----BEGIN CERTIFICATE-----
MIIEkjCCA3qgAwIBAgIQCgFBQgAAAVOFc2oLheynCDANBgkqhkiG9w0BAQsFADA/
MSQwIgYDVQQKExtEaWdpdGFsIFNpZ25hdHVyZSBUcnVzdCBDby4xFzAVBgNVBAMT
DkRTVCBSb290IENBIFgzMB4XDTE2MDMxNzE2NDA0NloXDTIxMDMxNzE2NDA0Nlow
SjELMAkGA1UEBhMCVVMxFjAUBgNVBAoTDUxldCdzIEVuY3J5cHQxIzAhBgNVBAMT
GkxldCdzIEVuY3J5cHQgQXV0aG9yaXR5IFgzMIIBIjANBgkqhkiG9w0BAQEFAAOC
AQ8AMIIBCgKCAQEAnNMM8FrlLke3cl03g7NoYzDq1zUmGSXhvb418XCSL7e4S0EF
q6meNQhY7LEqxGiHC6PjdeTm86dicbp5gWAf15Gan/PQeGdxyGkOlZHP/uaZ6WA8
SMx yk13EiSdRxta67nsHjcAHJyse6cF6s5K671B5TaYucv9bTyWaN8jKkKQDIZ0
Z8h/pZq4UmEUEz9l6YKHy9v6Dlb2honzhT Xhq w3Brvaw2VFn3EK6BlspkENnWA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 dla5cEilaUcne8IkCJLxWh9KEik3JHRRHGJo
uM2VcGfl96S8TihRzZvoroed6ti6WqEBmtzw3Wodatg VyOeph4EYpr/1wXKtx8/
wApIvJSwtmVi4MFU5aMqrSDE6ea73Mj2tcMyo5jMd6jmeWUHK8so/joWUoHOUgwu
X4Po1QYz 3dszkDqMp4fklxBwXRsW10KXzPMTZ sOPAveyxindmjkW8lGy QsRlG
PfZ G6Z6h7mjem0Y iWlkYcV4PIWL1iwBi8saCbGS5jN2p8M X Q7UNKEkROb3N6
KOqkqm57TH2H3eDJAkSnh6/DNFu0Qg==
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
MIIDSjCCAjKgAwIBAgIQRK wgNajJ7qJMDmGLvhAazANBgkqhkiG9w0BAQUFADA/
MSQwIgYDVQQKExtEaWdpdGFsIFNpZ25hdHVyZSBUcnVzdCBDby4xFzAVBgNVBAMT
DkRTVCBSb290IENBIFgzMB4XDTAwMDkzMDIxMTIxOVoXDTIxMDkzMDE0MDExNVow
PzEkMCIGA1UEChMbRGlnaXRhbCBTaWduYXR1cmUgVHJ1c3QgQ28uMRcwFQYDVQQD
Ew5EU1QgUm9vdCBDQSBYMzCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEB
AN v6ZdQCINXtMxiZfaQguzH0yxrMMpb7NnDfcdAwRgUi DoM3ZJKuM/IUmTrE4O
rz5Iy2Xu/NMhD2XSKtkyj4zl93ewEnu1lcCJo6m67XMuegwGMoOifooUMM0RoOEq
OLl5CjH9UL2AZd 3UWODyOKIYepLYYHsUmu5ouJLGiifSKOeDNoJjj4XLh7dIN9b
xiqKqy69cK3FCxolkHRyxXtqqzTWMIn/5WgTe1QLyNau7Fqckh49ZLOMxt /yUFw
7BZy1SbsOFU5Q9D8/RhcQPGX69Wam40dutolucbY38EVAjqr2m7xPi71XAicPNaD
aeQQmxkqtilX4 U9m5/wAl0CAwEAAaNCMEAwDwYDVR0TAQH/BAUwAwEB/zAOBgNV
HQ8BAf8EBAMCAQYwHQYDVR0OBBYEFMSnsaR7LHH62 FLkHX/xBVghYkQMA0GCSqG
SIb3DQEBBQUAA4IBAQCjGiybFwBcqR7uKGY3Or Dxz9LwwmglSBd49lZRNI DT69
ikugdB/OEIKcdBodfpga3csTS7MgROSR6cz8faXbauX 5v3gTt23ADq1cEmv8uXr
AvHRAosZy5Q6XkjEGB5YGV8eAlrwDPGxrancWYaLbumR9YbK rlmM6pZW87ipxZz
R8srzJmwN0jP41ZL9c8PDHIyh8bwRLtTcm1D9SZImlJnt1ir/md2cXjbDaJWFBM5
JDGFoqgCWjBH4d1QB7wCCZAA62RjYJsWvIjJEubSfZGL T0yjWW06XyxV3bqxbYo
Ob8VZRzI9neWagqNdwvYkQsEjgfbKbYK7p2CNTUQ
-----END CERTIFICATE-----

Set correct permissions for the directory:

sudo chown -R zimbra:zimbra /opt/zimbra/ssl/letsencrypt/

Confirm the owner is zimbra user.

$ ls -lha /opt/zimbra/ssl/letsencrypt/
total 32K
drwxr-xr-x. 2 zimbra zimbra 4.0K Jul  6 00:18 .
drwxr-xr-x. 8 zimbra zimbra 4.0K Jul  6 00:13 ..
-rw-r--r--. 1 zimbra zimbra 1.9K Jul  6 00:14 cert.pem
-rw-r--r--. 1 zimbra zimbra 1.7K Jul  6 00:14 chain.pem
-rw-r--r--. 1 zimbra zimbra 3.6K Jul  6 00:14 fullchain.pem
-rw-------. 1 zimbra zimbra 1.7K Jul  6 00:14 privkey.pem
-rw-r--r--. 1 zimbra zimbra  692 Jul  6 00:14 README
-rw-r--r--. 1 zimbra zimbra 2.8K Jul  6 00:23 zimbra_chain.pem

Verify your commercial certificate.

sudo su - zimbra -c '/opt/zimbra/bin/zmcertmgr verifycrt comm /opt/zimbra/ssl/letsencrypt/privkey.pem /opt/zimbra/ssl/letsencrypt/cert.pem /opt/zimbra/ssl/letsencrypt/zimbra_chain.pem'

Output should not give any errors or mismatch.

** Verifying '/opt/zimbra/ssl/letsencrypt/cert.pem' against '/opt/zimbra/ssl/letsencrypt/privkey.pem'
Certificate '/opt/zimbra/ssl/letsencrypt/cert.pem' and private key '/opt/zimbra/ssl/letsencrypt/privkey.pem' match.
** Verifying '/opt/zimbra/ssl/letsencrypt/cert.pem' against '/opt/zimbra/ssl/letsencrypt/zimbra_chain.pem'
Valid certificate chain: /opt/zimbra/ssl/letsencrypt/cert.pem: OK

Backup current certificate files.

sudo cp -a /opt/zimbra/ssl/zimbra /opt/zimbra/ssl/zimbra.$(date " %Y%.m%.d-%H.%M")

Copy the private key under Zimbra SSL path.

sudo cp /opt/zimbra/ssl/letsencrypt/privkey.pem /opt/zimbra/ssl/zimbra/commercial/commercial.key
sudo chown zimbra:zimbra /opt/zimbra/ssl/zimbra/commercial/commercial.key

Finally deploy the new Let’s Encrypt SSL certificate.

sudo su - zimbra -c '/opt/zimbra/bin/zmcertmgr deploycrt comm /opt/zimbra/ssl/letsencrypt/cert.pem /opt/zimbra/ssl/letsencrypt/zimbra_chain.pem'

My certificate deployment output is as shown below.

** Verifying '/opt/zimbra/ssl/letsencrypt/cert.pem' against '/opt/zimbra/ssl/zimbra/commercial/commercial.key'
Certificate '/opt/zimbra/ssl/letsencrypt/cert.pem' and private key '/opt/zimbra/ssl/zimbra/commercial/commercial.key' match.
** Verifying '/opt/zimbra/ssl/letsencrypt/cert.pem' against '/opt/zimbra/ssl/letsencrypt/zimbra_chain.pem'
Valid certificate chain: /opt/zimbra/ssl/letsencrypt/cert.pem: OK
** Copying '/opt/zimbra/ssl/letsencrypt/cert.pem' to '/opt/zimbra/ssl/zimbra/commercial/commercial.crt'
** Copying '/opt/zimbra/ssl/letsencrypt/zimbra_chain.pem' to '/opt/zimbra/ssl/zimbra/commercial/commercial_ca.crt'
** Appending ca chain '/opt/zimbra/ssl/letsencrypt/zimbra_chain.pem' to '/opt/zimbra/ssl/zimbra/commercial/commercial.crt'
** Importing cert '/opt/zimbra/ssl/zimbra/commercial/commercial_ca.crt' as 'zcs-user-commercial_ca' into cacerts '/opt/zimbra/common/lib/jvm/java/lib/security/cacerts'
** NOTE: restart mailboxd to use the imported certificate.
** Saving config key 'zimbraSSLCertificate' via zmprov modifyServer mail.computingforgeeks.com...ok
** Saving config key 'zimbraSSLPrivateKey' via zmprov modifyServer mail.computingforgeeks.com...ok
** Installing imapd certificate '/opt/zimbra/conf/imapd.crt' and key '/opt/zimbra/conf/imapd.key'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.crt' to '/opt/zimbra/conf/imapd.crt'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.key' to '/opt/zimbra/conf/imapd.key'
** Creating file '/opt/zimbra/ssl/zimbra/jetty.pkcs12'
** Creating keystore '/opt/zimbra/conf/imapd.keystore'
** Installing ldap certificate '/opt/zimbra/conf/slapd.crt' and key '/opt/zimbra/conf/slapd.key'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.crt' to '/opt/zimbra/conf/slapd.crt'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.key' to '/opt/zimbra/conf/slapd.key'
** Creating file '/opt/zimbra/ssl/zimbra/jetty.pkcs12'
** Creating keystore '/opt/zimbra/mailboxd/etc/keystore'
** Installing mta certificate '/opt/zimbra/conf/smtpd.crt' and key '/opt/zimbra/conf/smtpd.key'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.crt' to '/opt/zimbra/conf/smtpd.crt'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.key' to '/opt/zimbra/conf/smtpd.key'
** Installing proxy certificate '/opt/zimbra/conf/nginx.crt' and key '/opt/zimbra/conf/nginx.key'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.crt' to '/opt/zimbra/conf/nginx.crt'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.key' to '/opt/zimbra/conf/nginx.key'
** NOTE: restart services to use the new certificates.
** Cleaning up 3 files from '/opt/zimbra/conf/ca'
** Removing /opt/zimbra/conf/ca/ca.key
** Removing /opt/zimbra/conf/ca/6703d76b.0
** Removing /opt/zimbra/conf/ca/ca.pem
** Copying CA to /opt/zimbra/conf/ca
** Copying '/opt/zimbra/ssl/zimbra/ca/ca.key' to '/opt/zimbra/conf/ca/ca.key'
** Copying '/opt/zimbra/ssl/zimbra/ca/ca.pem' to '/opt/zimbra/conf/ca/ca.pem'
** Creating CA hash symlink '6703d76b.0' -> 'ca.pem'
** Creating /opt/zimbra/conf/ca/commercial_ca_1.crt
** Creating CA hash symlink '4f06f81d.0' -> 'commercial_ca_1.crt'
** Creating /opt/zimbra/conf/ca/commercial_ca_2.crt
** Creating CA hash symlink '2e5ac55d.0' -> 'commercial_ca_2.crt'

Restart the nginx or jetty services stopped earlier.

$ sudo su - zimbra -c "zmcontrol restart"

Host mail.computingforgeeks.com
	Stopping zmconfigd...Done.
	Stopping zimlet webapp...Done.
	Stopping zimbraAdmin webapp...Done.
	Stopping zimbra webapp...Done.
	Stopping service webapp...Done.
	Stopping stats...Done.
	Stopping mta...Done.
	Stopping spell...Done.
	Stopping snmp...Done.
	Stopping cbpolicyd...Done.
	Stopping archiving...Done.
	Stopping opendkim...Done.
	Stopping amavis...Done.
	Stopping antivirus...Done.
	Stopping antispam...Done.
	Stopping proxy...Done.
	Stopping memcached...Done.
	Stopping mailbox...Done.
	Stopping logger...Done.
	Stopping dnscache...Done.
	Stopping ldap...Done.
Host mail.computingforgeeks.com
	Starting ldap...Done.
	Starting zmconfigd...Done.
	Starting dnscache...Done.
	Starting logger...Done.
	Starting mailbox...Done.
	Starting memcached...Done.
	Starting proxy...Done.
	Starting amavis...Done.
	Starting antispam...Done.
	Starting antivirus...Done.
	Starting opendkim...Done.
	Starting snmp...Done.
	Starting spell...Done.
	Starting mta...Done.
	Starting stats...Done.
	Starting service webapp...Done.
	Starting zimbra webapp...Done.
	Starting zimbraAdmin webapp...Done.
	Starting zimlet webapp...Done.

Step 5: Test Let’s Encrypt SSL Certificate on Zimbra Mail Server

Open the Admin or webmail console of Zimbra collaboration server and check certificate details.

<img alt="" data-ezsrc="https://kirelos.com/wp-content/uploads/2020/07/echo/zimbra-mail-server-lesencrypt-ssl-1024×544.png" data-ez ezimgfmt="rs rscb8 src ng ngcb8 srcset" src="data:image/svg xml,”>

You now have Let’s Encrypt SSL certificate working on your Zimbra Server. For renewal follow below steps.

  • Stop Zimbra Services
  • Renew Let’s Encrypt SSL certificate
  • Then follow the rest of the steps from Step 4

Other Zimbra guides:

How To Restore Zimbra LDAP database from Backup

How To solve Zimbra zmconfigd not running/starting

How To Configure Microsoft Outlook for Zimbra

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