[Exim] AUTH LOGIN PLAIN and old e-mail clients

Hi,

I've just setup a PLAIN/LOGIN authentication on Exim 4.23 / FreeBSD 4.7 and
it works fine except for the two old client programs: MS Outlook Express
from 1998 or 99 and Calypso from 1999. The problem is that the clients don't
authenticate themselves although the are configured to do so. I took a look
at exim's log (in debug mode) and saw that:

exim sends:

...
10326 250-SIZE 10000000
10326 250-PIPELINING
10326 250-AUTH PLAIN LOGIN
10326 250 HELP
...

but the client answers:

10326 SMTP<< MAIL FROM: <test@???>
10326 SMTP>> 250 OK
10326 SMTP<< RCPT TO: test2@???

so it doesn't send any authentication data and is rejected by server.
I don't know why these old client programs behave so. The newer ones work
great.

I've also found that other servers give such answer to EHLO command:

...
250-AUTH=LOGIN PLAIN
250-AUTH LOGIN PLAIN
....

which differs from mine at the line: 250-AUTH=LOGIN PLAIN which is an
additional one.
Maybe the old client programs pay attention to this line and authenticate
only when received such line in answer to their EHLO command?

Regards,
Robert