After a reboot, I found my users unable to log in to their email and getting this message in their browser:

Code:
A network service error has occurred (zclient/io).
It would appear that the mailbox service is not coming up ...

$ zmcontrol status
Code:
Host mail.rhythix.com
        antispam                Running
        antivirus               Running
        ldap                    Running
        logger                  Running
        mailbox                 Stopped
                zmmailboxdctl is not running.
        mta                     Running
        snmp                    Running
        spell                   Running
        stats                   Running
a "zmmailboxdctl start" shows this ...

zmmailboxd.out
Code:
com.zimbra.cs.zclient.ZClientException: invoke cannot determine soap protocol in reply: <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"/><title>Error 503 SERVICE_UNAVAILABLE</title></head><body><h2>HTTP ERROR: 503</h2><pre>SERVICE_UNAVAILABLE</pre><p>RequestURI=/service/admin/soap/</p><p><i><small><a href="http://jetty.mortbay.org">Powered by jetty://</a></small></i></p></body></html>, server: localhost
ExceptionId:btpool0-2:1256281089582:f8186efc448b4762
Code:zclient.IO_ERROR
...
Error occurred during initialization of VM
Could not reserve enough space for object heap
I'm not sure if the heap space problem caused the problem or was a side effect of the problem.

$ prtconf -v | grep Memory
Code:
Memory size: 4095 Megabytes
$ zmlocalconfig mailboxd_java_heap_memory_percent
Code:
mailboxd_java_heap_memory_percent = 40

Thanks for any suggestions,
Steve Maring