How to create self-signed certificate for Zimbra mail server

Zimbra Collaboration Suite (ZCS), or Zimbra mail server, uses certificates to secure its operation and communication. If a certificate expires, Zimbra cannot operate. The solution is to create a new certificate. To create a certificate for Zimbra Collaboration Suite (ZCS), follow these steps: Creating a Self-Signed Certificate for Zimbra mail server

1. Run the following command to generate a Certificate Authority (CA).

   # /opt/zimbra/bin/zmcertmgr createca -new

2. Sign a certificate valid for 365 days.

   # /opt/zimbra/bin/zmcertmgr createcrt -new -days 365

3. Deploy the Self-Signed Certificate.

   # /opt/zimbra/bin/zmcertmgr deploycrt self

4. Deploy the Certificate Authority (CA).

   # /opt/zimbra/bin/zmcertmgr deployca

5. Check the certificate deployed to every service.

   # /opt/zimbra/bin/zmcertmgr viewdeployedcrt

Creating a self-sign certificate for a Zimbra Muli servers mail system

1. Create a Certificate Authority (CA) with this command:

   # /opt/zimbra/bin/zmcertmgr createca -new

2. Create a certificate to be signed by the Certificate Authority above (valid for 365 days) with these commands:

   # /opt/zimbra/bin/zmcertmgr createcrt -new -days 365 \ 
   -subject "/C=US/ST=CA/L=NVA/O=ZCS/OU=ZCS/CN=*.ezymailhosting.com"
   # /opt/zimbra/bin/zmcertmgr createcrt -new -days 365 \ 
   -subjectAltNames "mail1.ezymailhosting.com,mail2.ezymailhosting.com"

3. Deploy the certificate to all servers with this command:

   # /opt/zimbra/bin/zmcertmgr deploycrt self -allserver

4. After deployment, check whether it works on each server with this command:

   # /opt/zimbra/bin/zmcertmgr viewdeployedcrt