First of all, I am very inexperience with mail server administration setup etc.
Our company currently have an old mail server running in production with qmail along with courier-imap, and openldap for user authentication.

after doing some research I found Zimbra to be a good candidate to move to from our old qmail MTA which is not longer supported to Zimbra.

I have setup a new 64 bit VM server for testing purposes running redhat 6 operating system.
1. - I installed zimbra
2. - created a user account in zimbra that matches one of the accounts on the current mail server and send a couple of e-mails for testing and sending e-mails work
3. - used imapsync to sync a user account mailbox from current qmail server to zimbra and it works fine.
4. - Since our current qmail users authenticate through openldap server which is running on the same box as the qmal server. from the admin console in zimbra I would like to connect to this openldap server.
5. - After providing all the information such as the: ldaps://10.x.x.x port 636 SSL %u as the ldap filter the ldap bind username and password as well as an ldap user name and password to test settings. It does not work. I get the below error message:

How do I import a certificate from the current openldap server to the new server where zimbra is installed?

avax.naming.CommunicationException: simple bind failed: [Root exception is PKIX path building failed: xception: unable to find valid certification path to requested target]
at com.sun.jndi.ldap.LdapClient.authenticate(LdapClie
at com.sun.jndi.ldap.LdapCtx.connect( 0)
at com.sun.jndi.ldap.LdapCtx.<init>(
at com.sun.jndi.ldap.LdapCtxFactory.gezmprov mcf zimbraImapCleartextLoginEnabled TRUE
zmprov mcf zimbraPop3CleartextLoginEnabled TRUE
at com.sun.jndi.ldap.LdapCtxFactory.getUsingURLs(Ldap
at com.sun.jndi.ldap.LdapCtxFactory.getLdapCtxInstanc e(
at com.sun.jndi.ldap.LdapCtxFactory.getInitialContext (
at javax.naming.spi.NamingManager.getInitialContext(N
at javax.naming.InitialContext.getDefaultInitCtx(Init
at javax.naming.InitialContext.init(InitialContext.ja va:223)
at javax.naming.ldap.InitialLdapContext.<init>(Initia
at com.zimbra.cs.account.ldap.ZimbraLdapContext.<init >(
at com.zimbra.cs.account.ldap.ZimbraLdapContext.<init >(
at com.zimbra.cs.account.ldap.ZimbraLdapContext.<init >(
at com.zimbra.cs.account.ldap.LdapUtil.ldapAuthentica te(
at com.zimbra.cs.account.ldap.Check.checkAuthConfig(C
at com.zimbra.cs.service.admin.CheckAuthConfig.handle (
at com.zimbra.soap.SoapEngine.dispatchRequest(SoapEng
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:287)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:158)
at com.zimbra.soap.SoapServlet.doWork(SoapServlet.jav a:303)
at com.zimbra.soap.SoapServlet.doPost(SoapServlet.jav a:217)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:725)
at com.zimbra.cs.servlet.ZimbraServlet.service(Zimbra
at javax.servlet.http.HttpServlet.service(HttpServlet .java:814)
at org.mortbay.jetty.servlet.ServletHolder.handle(Ser
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(
at com.zimbra.cs.servlet.SetHeaderFilter.doFilter(Set
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(
at org.mortbay.servlet.UserAgentFilter.doFilter(UserA
at org.mortbay.servlet.GzipFilter.doFilter(GzipFilter .java:132)
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(
at org.mortbay.jetty.servlet.ServletHandler.handle(Se
at org.mortbay.jetty.servlet.SessionHandler.handle(Se
at org.mortbay.jetty.handler.ContextHandler.handle(Co
at org.mortbay.jetty.webapp.WebAppContext.handle(WebA
at org.mortbay.jetty.handler.ContextHandlerCollection .handle(
at org.mortbay.jetty.handler.HandlerCollection.handle (
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha
at org.mortbay.jetty.handler.rewrite.RewriteHandler.h andle(
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha
at org.mortbay.jetty.handler.DebugHandler.handle(Debu
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha
at org.mortbay.jetty.Server.handle(
at org.mortbay.jetty.HttpConnection.handleRequest(Htt
at org.mortbay.jetty.HttpConnection$ ntent(
at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:756)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa
at org.mortbay.jetty.HttpConnection.handle(HttpConnec
at org.mortbay.thread.BoundedThreadPool$ n(
Caused by: PKIX path building failed: xception: unable to find valid certification path to requested target
at n(
at erCertificate(
at essMessage(
at p(
at cord(
at ord(
at InitialHandshake(
at aRecord(
at 20)
Caused by: PKIX path building failed: xception: unable to find valid certification path to requested target