550 Mailbox Unavailable Errors on Incoming Mail

We are getting a couple of domains having trouble sending to our domain on
our SBS 2003 Server with Exchange 2003 SP1.

The two domains are based in 1. Italy and 2. Nepal.

This is the error they receive and we do not get their email. No address at
our domain will receive email from these domains.

Pls Help.

I post the two examples below. They both appear to use Oulook Express but
that doesn't seem to be the problem.

----- Original Message -----

From: "Mail Delivery Service" postmaster@mail01.evolv-e.it

To: senderemail@iltk.it

Sent: Tuesday, April 17, 2007 7:15 PM

Subject: Delivery Status Notification

- These recipients of your message have been processed by the mail

server:

to someone at my domain@fpmt.org; Failed; 5.3.0 (other or undefined mail
system

status)

Remote MTA mail.fpmt.org: network error

- SMTP protocol diagnostic: 550 Requested action not taken: mailbox

unavailabl

The problem may have nothing to do with your server at all; your Exchange
server isn't hosting fpmt.org's mail directly.

http://www.dnsreport.com/tools/dnsre...omain=fpmt.org

What is mail.fpmt.org running on, where is it, and who manages it?

Yes, my SBS server is hosting fpmt.org mail. mail.fpmt.org is the fqdn of
my sbs server

Our 1 MX record is:

10 mail.fpmt.org. [TTL=3601] IP=70.103.203.75 [TTL=3601] [US]

which is the corect IP address. .74 is our web server.

And all other mail gets to us, just a lot from those two domains below seem
to be bouncing back.

When I telnet to mail.fpmt.org on 25, I get this as a banner:
220 SMTP service ready

....which isn't a default banner for Exchange. Anything else
running/answering SMTP requests on your LAN?

Here's what I did:

telnet mail.fpmt.org 25
ehlo test.com
mail from:admin@test.com
rcpt to:paddy @ f p m t . com [am trying to keep you from getting
spam....but I entered it properly without spaces]
data
test test test

.....Up to this point it was OK...then I hit enter and a period/enter, to
submit. And immediately got:

550: Requested action not taken: mailbox unavailable.
Connection to host lost.

Either this isn't your Exchange server answering directly (which is what I
suspect....) or you've got some weird filtering set up.

I have a Watchguard firewall that it is probably hitting first.

Thanks. Now I know this is outside the scope of this group but do you have
any clues on what I could do to rectify the problem?

Any help here Paddy?

SMTP mail cannot be sent or cannot be received in Exchange Server
(disable the WatchGuard Firebox SMTP Proxy service)
http://support.microsoft.com/kb/895857

That may be of some help, once i figure out how to bypass the SMTP filter in
Watchguard. However, I notice that document does not mention the specific
error I receive, i.e. the particular type of 550 error and the 5.3.0

" - These recipients of your message have been processed by the mail server:
to someone at my domain@fpmt.org; Failed; 5.3.0 (other or undefined mail
system status)
Remote MTA mail.fpmt.org: network error - SMTP protocol diagnostic:
550 Requested action not taken: mailbox unavailable"

Not sure about the exact error type not being listed.

Configuring an SMTP proxy service
http://www.watchguard.com/help/lss/46/User/servic13.htm

I'll submit an incident with Watchguard to see if they have a fix. This is
all assuming that it is the firewall and not the SBS server that is
rejecting these emails.

Dollars to doughnuts it's the Watchguard config.

Yup. The SMTP Proxy policy. Even updating the software the problem still
exists. So had to remove the SMTP proxy on the watchguard and just use an
SMTP filter to resolve it.

Actually, do you have any idea where I can get a list of headers that I can
add to my existing list in my filter so I can keep the smtp proxy filter in
place? I couldn't tell from the emails that were bouncing what exact header
info was causing it to bounce.

Hi !

Non-delivery reports (NDRs) are system messages that report the delivery status of a message to the sender. The messages are a subclass of a general message information structure that is referred to as delivery status notifications. Delivery status notifications describe three different types of situations:

* Success (2.X.X numeric codes)
* Persistent transient failure (4.X.X numeric codes)
* Permanent failures (5.X.X numeric codes)
you can use a Kernel software to solve these types of issues in your outlook.