"550 5.7.1 <name@company.com>...Relaying denied. IP name lookup failed" Error in Exchange 2003

I have searched the web and tried about every solution I could find, but none of them fixed the relaying problem I have.

I am a college student, in addition to working in the IT department at my company.  I want to use IMAP to login to my school account and send/receive emails.  I'm able to receive them fine, but when I try to send to anyone I get the message above.  If I reply to a message I received on that account I usually don't have a problem.

Steps taken so far:
Added MX record to Exchange server in DNS forward lookup zone.
All other steps were reverted back to original settings when I discovered that they did not work.

We are using a Check Point SmartCenter server as our firewall.

If I try to resend the message, using Outlook's "Resend this Message" under the Actions menu, using my Exchange account to send and modifying the From to be my school email address I get a different error message:

The following recipient(s) could not be reached:

      name@email.com on 4/7/2006 10:10 AM
            You do not have permission to send to this recipient.  For assistance, contact your system administrator.

If I use my Hotmail account to send from I can change the From field and the message goes through fine.

RPC over HTTP is enabled, so of course I am using Outlook 2003.  This occurs whether I am at home on my laptop or logged in directly at work.  When I am on campus it happens less frequently, sometimes not at all.

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Sounds like the mailserver you are sending to is not accepting mail from your mailserver because IT has no reverse record on the ip-address.

See : http://support.microsoft.com/?kbid=164213 

Some mailservers today do this to get rid of spammers and as an unwritten rule you should have a reverse record on your smtp/mx server.  (Check with your school tech support for info)


NOTE: An Exchange computer that is configured as an open mail relay may be used to send spam. If other mail servers identify your Exchange computer as  spammer, your Exchange computer may be added to block lists. Therefore, you may have trouble when you send mail to other domains. To resolve this issue, you must reconfigure your Exchange computer so that is not an open mail relay. Then, you must remove your Exchange computer from the block lists.

As for your second error - do you have smtp authentication enabled (and the correct password) configured in your send mail options?

pyroman1Author Commented:
I had seen issues regarding the reverse record when searching prior to my post.  This simply refers to having a PTR to the exchange server in the reverse lookup zone, does it not?

I came across the second link you provided and had already performed all of the steps in it, no luck though.

Is your note meant as an indication that my Exchange server is setup as an open relay, or was that for informational purposes?  I was pretty sure I set it up to NOT be an open relay, based on another post here at Experts-Exchange from someone in the military (http://www.experts-exchange.com/Networking/Email_Groupware/Q_21618834.html).

For the last question, SMTP authentication is not an option for my Exchange account, so I will assume this means for the IMAP/SMTP account for school.  I don't know that that would be an issue, because I can send from the Hotmail account using the On Behalf Of feature in Outlook.  That said, I did already try this as a last ditch effort.

One final note, I have been doing IT for quite some time.  I just never had to do a whole lot with Exchange beyond the initial setup.  I'm in school so I can finally get a degree and get into research.  So feel free to help me get my hands dirty, so to speak. :)
Have you checked to see whether the school mail server is allowing mail relay or not? The open relay part is also one thing that may be a cause it. If that is not the case, make sure your firewall is not blocking (try shutting it off and test),

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The colleges in the NYC area (CUNYs, and some private colleges that I know of specifically) are locked up fairly tight.  I would expect other colleges around the country to be taking similiar security measures to prevent inappropriate use of school equipment.  As you can remember from the RIAA crackdown of "music sharing" especially imposing fines; the colleges have a vested interest to ensure that they are not sued on this or other fronts.

Ensuring that an email service is not used as a relay for spam and unknown mail would be one of the lateral security measures a school network administrator would take, especially since many colleges now employ WLANs on campuses.  Imagine the number of possible security breaches there.

Thats kinda what I was figuring. But I wasnt 100% positive this was the same for schools. Most ISPs do this too.
Hi Craig,
Schools were notorious spots for just about everything; pirating, pornography, viruses, hacking on various levels ( as well as a lot of good things like collaborations on software development).  The last couple of years especially with the RIAA lawsuits, CUNY (and I'm pretty sure other institutions) have been clamping down on security.  Using technology and legal warnings, they are trying to ensure that none of the faculty and students are using their accounts to conduct anything illegal; as well as ensuring that no one from the outside breaches the network to do the same.  One college has employed a very impressive array of HIDs on the faculty network.  
Email wise, no open relays, as well there are filters in place to ensure that student and faculty accounts can not be used to send email messages of spam proportions.

pyroman1Author Commented:
The school does not allow relay, so I seem to have to reconfigure my smtp server everytime I am on a different network in order to send emails using my school account.
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