Question : Why cant I access Imail web client remotely?

I have Imail 10 installed on a member server in my domain. I have all my users configured, and it sends and receives mail (POP3/SMTP) just fine.

I have "web access" enabled on the users in question.
I can access the web client from the server itself. (http://localhost:8383/IClient/default.aspx)
I cannot however access it remotely (http://igate.domain.local:8383/IClient/default.aspx)
I can ping the machine both by IP address and FQDN.

I didnt do the install. It shares the server with two other apps that have web interfaces (WSUS, which runs on 8585, and the antivirus, which runs on 4343). Both of those application's web interfaces work fine remotely.

Answer : Why cant I access Imail web client remotely?

is the firewall on the Email Server enabled.

Is DNS configured correctly for that server ?