[exim] Exim doesn't respond to STARTTLS

Hi,

[Disclaimer: I'm new to a lot of this stuff so advanced apologies if
this question it silly. I've have read the FAQ and googled quite a bit.
I'm using the Debian Sarge packages, so possibly I should be told to go
away and bother the Debian community :-) ]

I have configured SMTP auth and TLS on my server (as per some articles I
found somewhere) so I can now tell Thunderbird to use my Exim4 server as
the sending SMTP server with a username/password. It did work initially,
but for long periods it seems to fail when I send an email. I tried
telneting to port 25 to see what is going on, and it responds to my EHLO
but when I type STARTTLS it just does nothing. Eventually Thunderbird
seems to timeout and gives an error about the server being down.
Obviously something is broken at the Exim (or SSL) end, but where can I
expect an error message? There's nothing in mainlog.

As suggested somewhere in the FAQ I tried "exim4 -bh [my IP]" to debug
this, but it doesn't respond to STARTTLS in the same manner and doesn't
say anything that sheds any light on the problem.

Any ideas? Thanks!


Regards,
DaveB