Test scenario:
1. Start two server - live and backup (dedicated topology)
2. Kill live server
3. Before backup comes alive try to start producer connected to backup

In step 3. client is trying to connect to backup before backup comes alive and ends with exception:
javax.naming.NameNotFoundException: queue not bound
at org.jnp.server.NamingServer.getBinding(NamingServer.java:771)
at org.jnp.server.NamingServer.getBinding(NamingServer.java:779)
at org.jnp.server.NamingServer.getObject(NamingServer.java:785)
at org.jnp.server.NamingServer.lookup(NamingServer.java:396)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:303)
at sun.rmi.transport.Transport$1.run(Transport.java:159)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:155)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:255)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:233)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:142)
at org.jnp.server.NamingServer_Stub.lookup(Unknown Source)
at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:750)
at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:710)
at javax.naming.InitialContext.lookup(InitialContext.java:392)
at org.jboss.smartfrog.hornetq.SimpleSender.clientLogic(SimpleSender.java:161)

There is an interval (~15s in my case) in which clients are not able to connect. We think this could be problem for HA.