Ok, let's tell the story of this first. I used to have a Proxy 2.0 server where I had to use a wspcfg.ini file with the proxy client installed in order to publish SMTP and POP3 on my Exchange 5.5 Server. I had some issues with Proxy 2.0 (I don't remember them) and upgraded to ISA server. I used the same method with the ini files but ended up having problems in doing that because when the online defragmention of the Exchange Information Store happened it would peg the CPU thus eventually the mapping between my ISA and my internal SMTP service lost connection making me restart the Internet Mail Service daily on my Exchange server. After months of this annoyance I finally decided to publish my Exchange 5.5 POP and SMTP services which fixed my problems with having to restart my Internet Mail Service Daily.
Now the only problem I have which I haven't figured out is that if you're on the internal network and try and connect via SMTP/POP Client or even telnet to the POP3 and SMTP ports on the external IP ISA just times out with this request. Occaisonally I can get through but the majority of the time it times out.
Now when I used the WSPCFG.INI method this wasn't an issue at all but it seems to be one with my Server Publishing method.
The problem when you change the server info in Outlook 2000 it's thinks it's a new server and downloads every stored message from the server. If the server info stays the same then it doesn't try and download all the messages again.
the best solution for mobile users without a VPN connection is to use a split DNS setup. Make sure that the pop3/smtp FQDN servername is resolved differently if the users are inside or outside ISA. When inside, the name should resolve to the real internal address of the Exchange server. When outside, the name should resolve to the published IP-address (ISA external interface).
to properly implement a split DNS, you need at least two seperate DNS servers: an internal one and an external one. For the extenal DNS you have two options: - do it yourself, but then I place this DNS server on a DMZ interface (I never server publish a DNS server). - let your ISP handle the external DNS. This is my recommended configuration because the ISP should have already the needed infrastructure including backup DNS servers.
I currently have 2 DNS server that are running both the internal and external DNS. All of my internal machines are on a in the zone network.domain.com and the domain is doman.com for the internet. I could always make an internal DNS Server for this purpose but it's only for 1 client with 1 record that needs to be resolved different internally.
1) if you cann't change the DNS infrastructure use a PPTP VPN solution for the mobile users.
2) if you want to keep both DNS servers for internal use (primary and secondary DNS), define on them both domains but with the *real* IP's, and outsource the external visible DNS zone with the published IP's to your ISP.
3) if you don't need internally a primary and secondary DNS server, use one for the internal clients (define on them both domains but with the *real* IP's) and the other one *only* for the external visible DNS zone (only published IP's). The latter is server publish to the external world and *must* not be used by your internal clients.
Thanks for all your help. I think I have what I need to get it to work now. What I ended up doing was creating a new DNS server internally and creating the record mail.domain.com poimted at my internal IP and set the DNS server to forawrd all failed requests to my real DNS servers.
This works well because the machines that will use this DNS server are only DHCP clients which are my boss, visitors, and build up machines.
Well i read the all message regarding the SMTP, and i did follow almost everything but still not able to resolve my SMTP Problem, I have ISA Server installed with Mail Server on same machine, i have my own DNS Server, and its allow everything to route the request to the desires location, the problem is this that, My Mail Server which is MailerDaemon, is not able to send the mails outside, but it can recieves the mail from outside, when i tried to define the protocol for SMTP outbound in Server Publishing, it asks for the external IP, and shows nothing in browse box, i am connected to my ISP with Dedicated IP on Dialup connection, even i tried to define my ISP's Fixed IP Address into SMTP Protocol rule. But it says their is no external IP Address.