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Can't Receive Mail

Can't Receive Mail

Can't Receive Mail

First time setup of the Internet Mail Service on Exchange 5.5 SP3. Client is hosting mail, ISP is hosting DNS. Connection type is a DSL router NAT enabled(?) and port 25 opened up (?). Pinging the mail server by name returns the IP address of the router. Is this OK or should the mail server have a real IP? (has an internal IP 192.168.x.x).
Telnet to port 25 returns proper message.
My problem is that outgoing mail works, but incoming does not. I have watched the inbound ques but nothing makes it. I thought the server side config was pretty straightforward.
Any ideas would be greatly appreciated as this is certainly not my expertise.

Thanks in advance



RE: Can't Receive Mail

First, I would verify that your ISP has an accurate DNS entry for your MX record. It could be that your ISP is directing incoming traffic to the router instead of the server. If it is correct, then...

I'm not too familiar with NAT'ing, but I'm fairly certain that your mail server would need to have an externally routable IP address. External systems must be able to connect to your mail server on port 25. To test it, try telnet'ing to port 25 from outside of your network or from the other side of the router.

If systems external to your network can't connect to port 25 on your Exchange server, you won't be able to receive mail. This won't stop you from sending mail, though.

Hope this helps, let me know how it works out...


RE: Can't Receive Mail

Thanks for the excellent advice. I did check and found out that the DNS entry was pointing to the 192.168XX which is of course not routable. The correct IP address for the mail server is in fact the router address. The router then forwards port 25 traffic through to the private address. I learned alot in the past two days, in particular that you don't always trust the ISP!

Thanks again.


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