[META] Mail lossage

Hal Finney (hal@rain.org)
Fri, 19 Sep 1997 14:26:38 -0700

For a couple of weeks now I have not been able to send mail to the
extropians list from my home system. I think I may know the reason
why now.

I have a Linux system which connects via a dial-up line to a local ISP,
rain.org. I connect a few times a day for an hour or so to get mail
and check the web.

My machine has never been configured quite right. In particular, I've
never known what to put for the hostname and fully qualified domain name.
I don't have a registered domain name, so I just made one up:
crypt.hfinney.com. For the most part this has not caused problems; my
outgoing mail shows my return address as hal@rain.org, and I use a POP
client to pick up my mail from rain.org and download to my Linux system.

Mail to from rain.org to extropians worked, but mail from my Linux
system (which uses rain.org as an SMTP mail server) does not. I am able
to send mail to other addresses, though. Sending mail to extropians and
cc'ing it to other addresses gets to the other addresses OK, but it does
not show up on extropians.

This suggested that the extropians list was rejecting my mail when it
came from my Linux system but accepting it when it came from rain.org.
The only real difference (I think) is that a couple of the headers are
different. There is an extra Received header when I send from Linux,
claiming the mail came from crypt.hfinney.com, and the Message-ID also had
that domain name. I thought perhaps the extropians software was trying to
do a DNS lookup on that name, and not finding it, was rejecting the mail.

To try this, I changed my hostname to s27.term1.sb.rain.org. This is
typical of the dynamic hostnames assigned by the PPP server on rain.org.
Each time I dial in I will get a slightly different address, with the s27
replaced by whatever port I land on. Nevertheless this is a typical name
and a DNS lookup on it should succeed.

Since I've made that change, all my mail to extropians has gone through.
Now I don't know for sure that this change was the cause; it's also
possible that some other change was made simultaneously that actually
was the fix. I will need to try changing the host name back and see if
it makes a difference.

But for other people who have been having problems getting through to the
list, if you have any bogus hostnames, you might see if this is the cause.
It would also be interesting to know if there were any changes made to the
list software about two weeks ago which might have made it pickier about
domain names in some header fields.