Here is my issue:
I have my ZCS which working pretty well inside my network, but outside, i cannot send any emails using my smtp with TLS and authentification.
I found lot of thread about the configuration of smtp relay, so i configured my SIP SMTP via the admin web interface, by carefuly uncheck the dns lookup box.
But it still not working outside my network.
Please note that all the necessary ports are opened in my firewall and inside my network, with or without the relay configuration, everything working well.
Thank you all