From Zimbra :: Wiki

How to Change the Page Title

• Reasons why you may want to change:
  • If you are running more than 1 instance of Zimbra (say QA or Dev) and you don't want to get your instances of Zimbra confused when you are logged in to more than 1 at a time.
  • You just want to do the branding thing.

As zimbra user:

vi /opt/zimbra/tomcat/webapps/zimbra/WEB-INF/classes/msgs/ZmMsg.properties
[change value for zimbraTitle = <new value>]

vi /opt/zimbra/tomcat/webapps/zimbra/WEB-INF/classes/msgs/ZhMsg.properties
[change value for zimbraTitle = <new value>]

The first is for the advanced client and the second is for the basic client.

You will need to restart tomcat and clear your browser cache/restart browser to see change take effect

tomcat restart

In ZCS 5.0

As zimbra user (su - zimbra):

vi /opt/zimbra/jetty/webapps/zimbra/WEB-INF/classes/messages/ZmMsg.properties
[change value for zimbraTitle = <new value>]

vi /opt/zimbra/jetty/webapps/zimbra/WEB-INF/classes/messages/ZhMsg.properties
[change value for zimbraTitle = <new value>]

The first is for the advanced client and the second is for the basic client.

You will need to restart jetty and clear your browser cache/restart browser to see change take effect

zmmailboxdctl restart