Postfix server and CDO messages

[rando1000]

Our front-end office is Windows and makes extensive use of CDO messages sent from VBA. Recently, we switched from an external e-mail service to an internal postfix server. I know the external service used Linux based servers as well. Problem is, our CDO messages are not accepted by our server. Any idea what settings I might need to change to allow these messages access?

[prn]

I'll admit that I am not particularly familiar with CDO, and, in fact, I have used sendmail rather than postfix, but I can suggest some topics for investigation.

First, you know that the CDO messages generated by your office apps were sufficiently standard that the other mail server could handle them. I suspect then that your problem probably lies somewhere other than the CDO (which would be good). In fact, I would guess that the problem lies more in the configuration of the postfix server than in the office clients.

The first thing I would probably do is try to send a message manually. It's simpler than it might sound. Log on to one of the client boxes, let's say it's called "phobos" just for the sake of illustration. Also for the sake of the example, let's say your domain is bar.com, and your mail server is called deimos.bar.com. Open a command window. Here's a sample from when I do this from a linux box, deimos, using its own sendmail server: Telnet is useful for much more than interactive terminal sessions and port 25 is the standard mail server (SMTP) port.

The lines beginning with "Connected" or with numeric codes are prompt or feedback lines from the server. The other lines are what I typed:

$ telnet localhost 25
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
220 deimos.bar.com ESMTP Sendmail 8.13.8/8.13.8; Mon, 14 Jan 2008 13:15:50 -0500
helo deimos
250 deimos.bar.com Hello localhost.localdomain [127.0.0.1], pleased to meet you
mail from: <prn@deimos>
250 2.1.0 <prn@deimos>... Sender ok
rcpt to: <[e-mail]>
250 2.1.5 <[e-mail]>... Recipient ok
data
354 Enter mail, end with "." on a line by itself
subject: test
 
this is a test.
.
250 2.0.0 m0EIFo5E012640 Message accepted for delivery
 

but, if I connect to deimos from windows box phobos, I get:

c:\> telnet deimos.bar.com 25
220 deimos.bar.com ESMTP Sendmail 8.13.8/8.13.8; Mon, 14 Jan 2008 13:21:22 -0500
helo phobos
250 deimos.bar.com Hello phobos.bar.com [10.4.48.54], pleased to meet you
mail from: <prn@deimos>
250 2.1.0 <prn@deimos>... Sender ok
rcpt to: <[e-mail]>
550 5.7.1 <[e-mail]>... Relaying denied
 

I suspect that you may find something like that. "Relaying denied" is a very likely error message, in fact. You do NOT want to have an open relay. You will need to set up the mail handling rules on your mail server so that mail from your windows client boxes can be relayed and mail from outside your domain cannot be relayed to anywhere but your local boxes (if you do not serve the mail clients direct from the mail server ("deimos" in the above example).

HTH,
Paul