Yes. Zimbra server resolves smtp.fop.unicamp.br. However, in zimbra configuration I changed all entries to the real name logan.fop.unicamp.br to avoid any problems. smtp.fop.unicamp.br is a CNAME to logan.fop.unicamp.br.
After changes I always use the comand "service zimbra restart" to make effect on zimbra and "postfix stop/start" on postfix. I think strange to find related activity just in secondary server log. the primary (postfix) don't show any log when I try to send email of the secondary to the internet. It appear's that the message don't arrive to the primary... but someone is refusing the forwarding. Is it possible that zimbra is forwarding to authoritatives DNS instead to forward to primary?
I looked to DNS logs, but I didn't find anything. I think that my microsoft DNS aren't configurated to get this level log. It makes me not sure if the messages are being forwarded to correct server. Is possible I change the level zimbra log to get more information?