exim troubles - HELO

[Monique Herman <spam@bounceswoosh.org>]

So I go to subscribe to the slrn-user mailing list ... it sends me a
confirmation email ... I reply to it and get the following complaint
from exim:
<quote>
This message was created automatically by mail delivery software (Exim).

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

  slrn-user-request@lists.sourceforge.net
    SMTP error from remote mailer after HELO toadstool:
    host mail.sourceforge.net [66.35.250.206]: 550 Don't like your
HELO/EHLO. Hostname must contain a dot.
</quote>

So I telnet to port 25 of my machine and sure enough:
<quote>
220 toadstool ESMTP Exim 3.36 #1 Tue, 23 Sep 2003 19:19:50 -0600
</quote>

All references to my hostname in exim.conf are fully-qualified.
The line in /etc/hostname is fully qualified.
There was a line in /etc/hosts referring to simply 'toadstool', but I
changed that to the fully-qualified name, restarted exim, and still the
same deal.

Would I need to restart any process, or heaven forbid reboot the
machine, to get this working?

How can I get exim to report the fully-qualified name?

Thanks in advance for any advice you kind folk might be able to give me!

-- monique