I found out the problem Spring [1] was experiencing with Exchange. [2] Here's the email I sent her describing the problem:
It was thus said that the Great Spring Dew once stated:
> > Did the copy of the message that I forwarded you have the full headers on it? In case not, here it is. Maybe this will help.
>
Got it! I figured out what Exchange is doing that is causing this. Leave it to Microsoft to break SMTP this badly. Grab some popcorn and watch (lines with “>” are what I type, and lines with “<” are the computer's response):
>
```
> telnet tower.conman.org smtp
< Trying 208.235.96.122...
< Connected to tower.conman.org.
< Escape character is '^]'.
< 220 conman.org ESMTP Sendmail 8.8.7/8.8.7; Wed, 23 Aug 2000 15:05:58 -0400
```
Okay, here I connected (manually) to my mailserver. After a quick
>
```
> helo linus.slab.conman.org
< 250 conman.org Hello spc@linus.slab.conman.org [208.26.72.3], pleased to meet you
```
To initialize the connection, I then did:
>
```
> expn ------@conman.org
< 250 <|/home/spring/bin/connected@conman.org>
```
Then, I did the following:
>
```
> mail from:<------@conman.org>
< 250 <------@conman.org>... Sender ok
> rcpt to:<------@conman.org>
< 250 <------@conman.org>... Recipient ok
```
Okay, this tells the mailserver who the mail is from, and where it's going to. Then the actual message itself:
>
```
> data
< 354 Enter mail, end with "." on a line by itself
> From: ------@conman.org
> To: |/home/spring/bin/connected
```
Notice the To: line. I think what Exchange is doing is substituting the given address (——) with the expanded address (/home/spring/bin/connected), trying to be “helpful” but blowing the entire process up.
>
```
> Subject: This is a test
>
> This is a test. It won't go through.
> .
< 250 PAA03898 Message accepted for delivery
> quit
< 221 conman.org closing connection
< Connection closed by foreign host.
```
And the message is accepted, but during processing will be rejected and a message bounced back.
Nice, eh?
-spc (Bloody Exchange … )
Informing Mark [3] about it, he thinks (much to his regret) that Exchange might be allowed to do that as part of the SMTP protocol. I'll have to check up on that and see.