Mail flow problem between EXCH2000 and EXCH2003 server in the same organization

[ammen...@gmail.com]

Hello to all

I have a Exchange 2000 server SP3 with post SP3 update rollup
installed on a Windows 2000 Advanced Server SP4 with all the requested
hotfixes. The Windows 2000 Server is also a Domain Controller and a
Global Catalog.
Now i am migrating to a clustered instance of Exchange 2003 SP2 on a
Windows 2003 R2 SP2.
No antivirus software is installed on the servers. The antivirus/
antispam protection is performed by a Symantec Mail Security System
5.0 box placed in the DMZ connected through a SMTP connector to the
Exchenge organization.
No firewall are placed between the 2000 and the 2003 servers, due to
the fact that they reside on the same lan.

My goal is to let the two servers coexist while moving the mailboxes
from the old 2000 to the new 2003.

I created a test mailbox and placed it on the new server, did some
tests and noticed this strange behaviour:

- All the mail from the EXCH2003 to the EXCH2000 server (internal
mail) or to the SMTP connector (internet mail) is delivered
succesfully.

- All the mail to the EXCH2003 server, both from the EXCH2000 or the
SMTP connector is stuck in a queue on the EXCH2000 server with the
error "The remote server did not respond to a connection attempt". The
event log says the same thing.

I checked the connectivity between the 2 servers on port 25 and it
works fine, and also the DNS is configured properly.

So i checked on the internet and i came across the Exchange
Troubleshooting Assistant, i ran it on the server selecting the
appropriate taks, and it returned me this error:

Mail acceptance failure Name: EXCH2003.DOMAIN.COM
Remote server ECH2003.DOMAIN.COM failed the mail acceptance test. BDAT
command: Respond = . Check for firewalls and applications that can
possibly block the BDAT command.

All the other tests were succesfully.

I obviously checked for firewalls or antivirus that may prevent the
BDAT command to run but nothing found.

I unfortunatley ran out of Iideas (at least because I thought that the
coexistance between the servers was the easy bit....:-))

Any kind of help would be very very appreciated

Thank you very much in advance

Ammendolia Fabio
Immergas IT Manager
Via Cisa Ligure 95
42100 Brescello (RE)
ITALY

[Andy David {MVP}]

Any smarthosts defined on the SMTP virtual server?

[ammen...@gmail.com]

On 22 Mar, 20:54, Andy David {MVP}

<ada...@pleasekeepinngcheesebucket.com> wrote:
> Any smarthosts defined on the SMTP virtual server?

Sorry, I forgot to mention...

Before the installation of the EXCHC2003 server there was a smart host
(the Symantec Mail Security box) configured on the SMTP virtual server
of the EXCH2000.
After the new installation, i removed all the smart host and
configured an SMTP connector using both server as local bridgehead and
using a namespace of * to allow all the internet mail flow through the
connector.

Best Regards,