SMTP + IMS

[ElijahBaley]

Hi

I am to install Exchange Server 5.5 and need some advice as to the precedure for changing from a POP3 based system (ISP hosted)to SMTP.

We have a NT network and connect to our ISP via a ISP configured router through a 256k leased line.

My first concern is our internal IP range, we have a private (non-legal) internal scheme, Our PDC (NT) has a static address of 10.10.10.5, it lists the default gateway as 10.10.10.1 (router installed by ISP) it runs DHCP and hands out addresses in the range 10.10.10.10 - 10.10.10.99 our client computers access the internet simply by addressing the PDC through the LAN (no proxy/no scripts) which then I assume addresses the gateway and passes the request out through the router, through our leased line to our ISP's DNS server's.

We have a BDC 10.10.10.6 and it is my intention to set-up what will become our Exchange server as a Member server with the address 10.10.10.7

OUTBOUND MAIL

Now this is where it gets a bit tricky, it seems to me that in order to configure the Exchange server for outbound mail all I need to do is to set-up the Internet Mail Service to forward all messages to host (ISP DNS server) which should not be a problem as long as I set-up the default gateway on the member server to point to the router (10.10.10.1)

INBOUND MAIL

Now this is where it gets very tricky, at some stage we are going to have to switch from POP3 to SMTP and this is where my knowledge breaks down a bit - I believe that with POP3 we reach out and negotiate the retrieval of mail and that with SMTP the ISP directs it to a address - my big question is "will the ISP be able to direct the SMTP stream to our member server, internal address 10.10.10.7 ?"

Does any of this make sense, am I on the right track, will it all go horribly wrong on D-Day ???

I could really use some quality advice on this subject - there is no particular urgency as I do not expect to go ahead with this for a few weeks.

Thanks for any advice,

gjdf1

 

[msexchangesa]

Regarding OUTBOUND mail, You would point your outbound IMS to your ISP's SMTP server (not the DNS server).

Regarding INBOUND... It sounds like your ISP has given you only one IP address - the one on the public side of your router. So your ISP could not route SMTP traffic directly to your internal SMTP server. They can't see it. All they see is the public side of your router. You could try configuring your router to "forward" traffic on TCP port 25 (SMTP port I think) to the internal address of 10.10.10.7. That might work. I have a little LinkSys router at home and it allows me to do this.

Check your contract with your ISP. Unless you have a business account that allows servers, your ISP may not appreciate you running an SMTP server. I know my home's ISP scans their network for port 25, looking for residential users who are running high-volume SMTP servers.

 

[Guest_imported]

You will need to protect your LAN with at least a device the previous poster suggests or setup a proxy server and use software such as surrogate socket which forwards smtp traffic to your internal ip.

 

[Guest_imported]

You will need to protect your LAN with at least a device the previous poster suggests or setup a proxy server and use software such as surrogate socket which forwards smtp traffic to your internal ip.

 

[ElijahBaley]

Thanks for your replys guys - I have some further information and another question: -

We do have a business account with our ISP and they are aware of our intention to host our own mail server - in fact they were aware of this when they installed our 256kbps leased line and router.

The router is leased from ISP and has been/will be configured by them.

If the router is configured on port 25 to forward "traffic" to my internal 10.10.10.7 - does this enable a security breach, allowing access to our LAN ?

Graham