error 550 not local host

First thing... you say that "specifically allowed relay from any host on my network". Have you done that by subnet? Is your firewall on the same subnet? If so you have just turned yourself in to an open relay. Change it back to not allowing anyone to relay.

You don't need to change anything if all the clients are connecting with Outlook configured as an Exchange client. If you have clients connecting via POP3 or IMAP and then sending via SMTP then you will need relaying. Use authenticated relaying instead - so that the clients authenticate to relay.

On to the actual error - does that happen no matter what domain you send the email message to?
If you use OWA on the Exchange server does the same error occur?

Have you got any SMTP Connectors configured within Exchange?

It would also help if you let us know what version of Windows Exchange is installed on, and the version of Exchange.

Simon.
Exchange MVP

> On to the actual error - does that happen no matter what domain you send the email message to?
If you use OWA on the Exchange server does the same error occur?

Well, I have not been experiencing this...I have one user in particular that is sedning to a couple specific addresses and it bounces everytime.  Also, i have some users of OWA that have been experiencing this to on certain addresses as well.

> Have you got any SMTP Connectors configured within Exchange?

I'm not sure if i have SMTP connectors configured.  Shoud I?  And if you could talk breifly about their significance that would be great.  Exchange is not my area of expertise:(

I am running Exchange 2000 Sp3 on Windows 2000 Server sp4.

Also, i reversed the change i made regarding relaying..thanks for the heads up.

i also tried sending an email to the same address in question and received a bounced message.  I have another use that received this error:
---------------------------------------------------------------------------------------------------
The following recipient(s) could not be reached:

user@domain.com on 4/20/2005 11:09 AM

The e-mail account does not exist at the organization this message was sent to. Check the e-mail address, or contact the recipient directly to find out the correct address.

<acadiasrv.acadia #5.1.1 smtp;550 5.1.1 <user@domain.com>... User unknown>
-----------------------------------------------------------------------------------------------------
What's interesting is i sent a test to the same user as above from a pop3 account and it also was bounced...but with a different message:
-----------------------------------------------------------------------------------------------------
When trying to deliver your message, the mail server at vipowernet.net encountered problems with the following addresses:

For <user@domain.com>, Invalid Domain (domain.com)

For a more detailed explanation see http://netwinsite.com/surgemail/deliver_failed.htm
------------------------------------------------------------------------------------------------------
vipowernet.net is my primary ISP...could the root of all these issue be my ISP's mail server? But the fact that this happens  when we send from exchange would rule out the problem being the ISP mail server?  

Also, i ran a mail test from dnsreport.com on the above address and it checked out ok.  

It certainly looks like this is a problem outside of your control. The remote domain could be misconfigured, or the ISP has DNS issues.

The first error means what it says - the server that Exchange tried to connect to (by looking up the MX records) doesn't have a user with that name.

The second error also means what it says - the server that tried to deliver the message (the ISPs SMTP server) couldn't find the server.

A real mess.

Simon.

i think it is safe to assume that my Exchange server is not misconfigured as we only recetnly have been experiencing this and nothing on my Exchange server has changed.  The fact that this last error included my ISPs mail server leads me to believe that there is an issue with the ISP.  AS for why mail sent to these certain address from exchnge are getting bounced i am still uncertain.  But again, i dont think it is my end.  However, i do need to prove to my end users that it is not our exchange server.

> The first error means what it says - the server that Exchange tried to connect to (by looking up the MX records) doesn't have a user with that name.
 
The dns report got a successful response from the email address in question.

The DNS report will not be using the same DNS servers that your ISP is using. If the ISP has inaccurate information then it could still generate the error message.

For example, if the remote domain has recently changed MX records, but the original server is still alive, and your ISP has the old information, then the email would be sent to the old server. The email would then bounce.

Simon.

good point

Just going through some of the old outstanding questions as it is quiet...

Has this problem been resolved?
If you need clarification on any part of the responses above, please post back.

Otherwise you need to close the question by awarding points, or posting in the Support Topic Area (top right corner) with a link to this question asking for the moderators to close the question for you without awarding points.

Simon.

I think what has not been considered is that the recipient could be routed through messagelabs or the like, depending on the config of their towers I would say it could be a sync issues with the towers in that region.