I have a problem related a slow link access to a SMTP server, I am thinking a way to boost SMTP delivery using MUAs. My remote mail server configuration is really simple a Linux box with SMTP and POP3 services running and PAM authentication.
I will use dummies IP address from this post, so this can help anyone on the net.
SMTP server IP: 10.0.0.1 / 24 (External network) DNS FQDN: ns.corp.net CNAME: pop.corp.net Internal network address are: 192.168.100.x/24 DNS suffix: corp.net
On my network, I have an ISA 2004 EE server that control the network, I have configured my ISA to allow SMTP traffic to External network, but as I said before, the SMTP delivery is very slow. Everytime my users want to send mails it takes about a 1-5 minutes to deliver the message. I have configured at MUAs to Outgoing and Incomming mail server address the pop.corp.net.
I would like to use my ISA box to capture all the SMTP traffic redirected to my 10.0.0.1 server and use the ISA box as mail relay and have it to handle delivery to the remote mail server.
I was reading the Publishing Terminal Servers with ISA Firewalls (2004) v1.1 article at http://www.isaserver.org/articles/2004pubts.html, but from my reading I clearly understand that default port forwarding configured at Publishing rules are applied only to external -> internal network, not viceversa.
Could anyone help me to have the ISA box capture the SMTP traffic destined to my remote mail server and so my ISA box can use its local SMTP service to send mails?