Hello all,
I have a mail problems with very little information to solve it.
I'm hoping someone else has come across this before and can provide some hints.

Our ISP relays the MX records destined to our domain directly to the mail
server.
The server is behind a firewall on a private network.
The firewall directs any smtp requests to the mail server.
This all worked quite well until three days ago.
Since feb. 1 we do not recieve mail from outside our ISP's network anymore.
Sending mail to anywhere is no problem.
Recieving mail from people with the same ISP is also no problem.
Mail from outside the ISP's network yields the following message in exims
mainlog:

2005-02-03 10:43:28 SMTP protocol violation: synchronization error
(input sent without waiting for greeting): rejected connection from
H=psmtp01.wxs.nl [195.121.6.56]

The configuration of our mailserver has not changed on feb. 1, but our ISP
has changed to a different mail-relay server on that date.
The ISP insists that the problem must be a configuration error on my server,
but he doesn't provide me with any pointers as to what has changed in his
configurations.
Since the start of this problem correlates very well with the commissioning of
his new servers, I suspect that there must be some sort of mismatch between the
configuration of the two servers.

Does anyone recognize this. I do not know which conf parameters to look for.
I tried switching RFC1413 callbacks on and off with no result.
If it is not my configuration, how do I convince my ISP to check his again?

Best regards,

Arij van Berkel

NB: please respond to the group as I cannot recieve mail.