How does email security appliance forwards mail to mail server
I'm trying to track down an issue discussed in another thread. I'm trying to do a packet capture with wireshark showing the comm.. between our email server and the ESA. Mail server, ESA and capturing PC is on the same VLAN. I see nothing between the email server and ESA. Our firewall forwards all email traffic to ESA. Mail server sends all outgoing email traffic to ESA. TLS is turned on. Why am I not seeing anything with the packet sniffer?