Exchange server malarkey

[motorollin]

Another overly elaborate and complex problem :-D

The Exchange server at uni (lets call it exchange.xxx.ac.uk is not accessible from outside the uni intranet. But the university provides Outlook Web Access on the web server owa.xxx.ac.uk. I wanted to configure a mail client on my home computer to connect to the Exchange server instead of using Outlook Web Access (which is horrible). I made an assumption that owa.xxx.ac.uk was an alias to a web server running on the Exchange server itself, and I was right: if I configured my mail client with the Exchange server address "owa.xxx.ac.uk" it worked. I could see all my Exchange folders, read emails, move them around, delete them etc.

The problem comes with sending. owa.xxx.ac.uk does not work as an outgoing mail server, so I had to use my ISP's SMTP server for sending. Of course, my ISP's SMTP server doesn't know how to resolve exchange.xxx.ac.uk, so if I want to send an email to somebody@exchange.xxx.ac.uk, it bounces saying it can't resolve the host.

Short of convincing the university to expose the exchange.xxx.ac.uk to the Internet, is there any way around this? Maybe a local SMTP server which has exchange.xxx.ac.uk in its hosts list so that it can be resolved to the IP address of owa.xxx.ac.uk. I don't actually know if this would work though, since although owa.xxx.ac.uk seems to allow access to the user's mailbox, I don't know whether it is running an inbound mail service.

:crazy: :crazy: :crazy: :crazy: :crazy:

[motorollin]

Indeed :-) I have had some additional thoughts about this. It would be absurd if the Exchange server did not allow messages to be sent from outside the university network. That would mean people could only receive emails from other people with accounts on the Exchange server, not from outside. That can't be the case.

I think the problem is that existing messages in the mailbox are being viewed by a user who is logged on to the Exchange server (IOW I am viewing the mailbox on the server). That means the sender address it shows me is the Exchange address, not the SMTP address. If I could get it to display the SMTP address instead of the Exchange address, then it might reply to that address (which must be accessible from outside the university network)

[motorollin]

I have an SMTP server provided by my ISP, but the problem is that it doesn't know how to resolve exchange.xxx.ac.uk (because it is not published in public DNS servers). The idea behind running a local one is that I can force it to resolve exchange.xxx.ac.uk using a hosts file. The alternative is to try to get the mailbox to show the sender's external (SMTP) email address instead of the internal (Exchange) address, which should be resolveable by public DNS servers.

[motorollin]

But you won't be able to send...

[motorollin]

I can't use SMTP to send because the reply address provided by the Exchange server is an address which is only valid within the Exchange. It doesn't work if you send from outside (i.e. through SMTP) So I either need to send through the Exchange server, or send to an SMTP server which has a host entry to allow it to resolve the address of the Exchange server.

[motorollin]

adolescent wrote:
It's quite possible, and normal, for the SMTP gateway to be seperate from the OWA.  And, in fact you're probably hitting a front end server not the actual Exchange server itself.

Ahh, so the OWA server is a separate box which acts as a gateway to the Exchange, right?

adolescent wrote:
Two easy options.  Ask your network administrator for the SMTP server address, or send yourself an email from inside and you may be able to discover the gateway name by inspecting the mail headers (provided they use the same SMTP gateway for incoming and outgoing messages).

Just tried it. There are quite a lot of "Received:" lines in the headers, presumably where the message is getting passed from one server to the next. The first ones in the chain resolve to 10.x.y.z addresses so are only accessible from inside. The last server before it gets to my ISP is mailcluster.xxx.ac.uk, which resolves to 193.x.y.z. AFAIK this is a public IP address, so I tried to telnet in on port 25 to see if there's an SMTP service running, but it timed out.

--
moto

[motorollin]

Ok, I sent a message *to* my Uni account and examined the headers of the message which was delivered, and found some different servers. One of them, lets call it server1.xxx.ac.uk, is running an SMTP server which is accessible from outside. I can Telnet in to it:

$ telnet server1.xxx.ac.uk 25
Trying xxx.xxx.xxx.xxx...
Connected to server1.xxx.ac.uk.
Escape character is '^]'.
220 server1.xxx.ac.uk ESMTP ready; send us your mail, but not your spam.
HELO
250 server1.xxx.ac.uk Hi [xxx.xxx.xxx.xxx] [xxx.xxx.xxx.xxx]; I am so happy to meet you.


But when I configure it as the outbound server in my mail client, I can't send messages through the server and it asks me to verify the settings. If I use the "Connection Doctor", it checks it and says "Connection to server succeeded, no login required".

:-?

[motorollin]

The way I see it, it's connecting ok but fails when it tries to actually send anything. I'm going to read up on SMTP and then try sending a message through the University server over Telnet. That way if I get an error at any point I'll see it in the Telnet session.

[motorollin]

Ok, here's what happened when I tried to send an email through Telnet, directly to the SMTP server:

$ telnet smtp.xxx.ac.uk 25
Trying xxx.xxx.xxx.xxx...
Connected to smtp.xxx.ac.uk.
Escape character is '^]'.
220 smtp.xxx.ac.uk ESMTP ready; send us your mail, but not your spam.
HELO
250 smtp.xxx.ac.uk Hi [xxx.xxx.xxx.xxx] [xxx.xxx.xxx.xxx]; I am so happy to meet you.
MAIL FROM:
250 , sender OK - how exciting to get mail from you!
RCPT TO:
550 Spamhaus hit - http://www.spamhaus.org/query/bl?ip=xxx.xxx.xxx.xxx
Connection closed by foreign host.



I followed the "Spamhaus" link, and I was directed to a page which said that "This IP range has been identified by Spamhaus as not meeting our policy for IPs which should deliver 'direct-to-mx' mail to PBL users." So it looks like the Uni Exchange server rejects emails from IP ranges which are not identified as being from legitimate ISP SMTP servers (or rather are identified as NOT belonging to them).

So I'm stuffed :-(

[motorollin]

In a last ditch attempt to get this working, I have emailed my ISP and asked them if they can add an entry to their SMTP server to resolve exchange.xxx.ac.uk to the IP address of smtp.xxx.ac.uk. Hopefully it's that simple, and they will be prepared to do it.

[motorollin]

As long as that? Blimey, you need more practice!

[motorollin]

Oh that poor, violated sock... :-P
Hey, we can trash this thread without feeling guilty since it's one of mine :-D

[motorollin]

Right, got a reply from my ISP. They are reluctant to make static entries their end for the uni MX server, in case anything changes at the uni end which screws up their settings and requires further changes. They have suggested that I ask the uni to put CNAMEs for the servers in to their zone. Unfortunately the IT department at uni don't even bother to return my emails :roll:

[motorollin]

Or just put up with OWA until I graduate in 2 years :roll: