[Exim] SMTP compatibility issue

Hi,

I am involved in the development of YAMS (Yet another mail server).

We seem to be able to talk to most servers with no problems, but
we are having a problem with two versions of exim that have tried
to talk to our server. The versions are 3.35 and the other is
4.3.

I should add that our server is not finished and still requires
some work, any pointers are appreciated. Server can be
reached with 'telnet id.synatech.com.au 25'. A valid
recipient is 7j36hwgb@??? - its a test
address so spam away. Ignore the 'java.z1', and the
certificate is just for testing purposes.

When exim calls our server, the conversation goes like this -

220 java.z1 Borg SMTP 1.0 - you will be assimilated
EHLO exim-colo-01.whoc.theplanet.co.uk
250-HELP
250-STARTTLS
250-AUTH=LOGIN
250 AUTH LOGIN
STARTTLS
220 Ready to start TLS
/*TLS session starts*/
220 java.z1 Borg SMTP 1.0 - you will be assimilated
EHLO exim-colo-01.whoc.theplanet.co.uk
250-HELP
250-STARTTLS
250-AUTH=LOGIN
250 AUTH LOGIN
MAIL FROM:<exim-users-admin@???>
RCPT TO:<7j36hwgb@???>
250 OK
DATA
354 Start mail input; end with <CRLF>.<CRLF>

At this point our server times out, waiting for
the <CRLF>.<CRLF>. Our debug log reveals that exim
has sent 'QUIT\r\n', after getting the 354 response.

The 354 response is copied from RFC2821, so I am hoping
that is OK.

With Exim being the more mature code, I would have to
think that the problem is with our server, so any help
understanding why the above is happening is appreciated.

Regards

Simon