Hosting static files on Zimbra Mailbox Store
From Zimbra :: Wiki
To host static content such as logos or banners on the mailbox store node for reuse on signatures et similia, we can reuse the jetty instance within Zimbra. Generally speaking, it's not advisable to host big files for general use though.
1. Copy files to /opt/zimbra/jetty/webapps/zimbra/public/
2. Check that ownership is zimbra:zimbra for the hosted files, and attributes are allowing readability.
3. Files are now reachable via http://<zimbraHostName>/public/<fileName>.
Https would work as well, but having self-signed certificates might create issues for client-side warnings when trying to reach them on the client side. If possible and allowed as security policy, http-only URLs should be advertized for external use.
If you have a multi-server installation, you might want to refer to: http://wiki.zimbra.com/wiki/Hosting_static_files_on_Zimbra_Proxy