This small organization has about 10 users running Outlook 2003 SP3 connected to Exchange Server 2003 mailboxes. They can send and receive email just fine through their Exchange accounts.
A couple users have POP3/SMTP accounts set up in Outlook along side the Exchange accounts. The POP3 and SMTP servers are hosted by an external mail hosting company. These servers work just fine from other networks. The users can receive email through the POP3 server just fine.
But when they try to send email through the SMTP server (by clicking the Account dropdown box in a new message and choosing the alternate SMTP account), they receive the following error message email in their Inbox a second or two after hitting Send:
From: System Administrator
Sent: Tuesday, December 16, 2008 5:03 PM
To: information@smtpdomain.com
Subject: Undeliverable:
Your message did not reach some or all of the intended recipients.
Subject: the meeting
Sent: 12/16/2008 5:03 PM
The following recipient(s) cannot be reached:
John Smith on 12/16/2008 5:03 PM
550 User jsmith@domain.com not found.
(Domains/usernames/email addresses/etc. have been changed for privacy).
The email address jsmith@domain.com is a known, good email address. It doesn't matter what address they send to. They can even send to an email address that exists on the internal domain / Exchange Server, and still get the same error. I've deleted and recreated the POP3/SMTP accounts in Outlook. I've tried using different, known, good POP3/SMTP servers and get the same exact undeliverable email.
This problem started happening after we ran into a complicated issue on the Exchange Server (A couple months ago I deleted a mailbox which was part of a group of mailboxes/users that receive Non Delivery Reports. When the next Non Delivery Report was sent to this mailbox, another NDR was generated because the mailbox did not exist. That NDR was also sent to the mailbox, creating an infinite loop of NDRs, which were sent to everyone else in the group. It created about 40,000 NDRs before I found out the next morning and stopped it. I turned off NDRs and made several other changes to fix that problem. Now after that problem was resolved, this new SMTP Error 550 problem is occurring).
Any help would be greatly appreciated as I've looked for help on this before and no one seems to be able to help!
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I would start at the port level. Follow these two documents how to test connectivity for pop & smtp
pop3 http://pages.prodigy.net/m
smtp http://technet.microsoft.c
Do these test, if you get success on both test then you will know that its not the connections (network provider), not the firewall, and is the client. But if the test fail you will need to look at the firewall, or network provider, or possible the hosted exchange server configuration.
Thanks for all your suggestions.
I have a correction: the user I'm working with on this problem is now able to send email out through this external SMTP server to recipients -outside- this domain (Yahoo, Hotmail, xyzcompany.com, etc.).
The only recipients they cannot send to are mailboxes on this internal domain.
@Sharkbot: There's no more specific error number than 550. I copied and pasted the error message exactly from the Undeliverable email the user receives. Also I checked the Access tab >> Connection dialog and no users are denied relay/send permission. I added the Domain Users group and gave them full send/relay permissions.
@Daveatwork: I added the IP address corresponding to the SMTP server to the list of servers allowed to relay. Made no difference.
I telnetted into smtp.externalserver.com (changed from original), from the Exchange Server:
220 CFD28.externalserver.com ESMTP MailMax 5.5 Thu, 18 Dec 2008 12:49:10 -0600
HELO company.com
250 CFD28.externalserver.com Hello [64.62.27.58] Pleased to meet you
MAIL FROM:information@externals
250 <information@externalserver
RCPT TO:jsmith@company.com
550 User jsmith@company.com not found.
RCPT TO:myemailaddress@hotmail.
250 Recipient <myemailaddress@hotmail.com
Obviously I changed the domains for privacy.
smtp.externalserver.com represents the SMTP server they are sending through.
company.com is the domain of the organization in question.
As you can see, it allows me to send to a Hotmail address (or Yahoo, Microsoft, etc.). But when I try to send to an email address on their specific domain it says "not found."
I think this is because the SMTP server is part of the hosting company which also hosts this organization's website ("company.com"). I will send the results of this telnet session to their support and see what they think.
Let me get it strait, internal to internal local domain is ok, internal to external broke and external to internal broke, correct? If so it sounds like one or both shevers are thinking they dont handle domain.com and generate the 550 relay. Can you telnet from the hosted server to your internal Exchange?
@Daveatwork: I know it gets a little confusing when I have to change the domains for privacy reasons, so let me clarify by making up names.
Let's call the company that I am the IT consultant for Healthbiz. Their domain is Healthbiz.com.
Their Exchange accounts in Outlook send/receive through this domain.
They also own another company, called Balance.org. They have POP3/SMTP email hosting for Balance.org through an external hosting company, CFDynamics. In Outlook, a user (John Smith, johnsmith@healthbiz.com) uses a POP3/SMTP account that receives email through pop.balance.org, and sends email through smtp.balance.org. The email address is information@balance.org.
-- John can receive email just fine through both johnsmith@healthbiz.com and information@balance.org (both internal and external).
-- John can send email through johnsmith@healthbiz.com just fine, to internal and external recipients.
-- John can send email out through information@balance.org, but only to external recipients.
-- If John tries to send email from information@balance.org to his own Exchange email address, johnsmith@healthbiz.com, he immediately gets the Undeliverable email.
I am on a different network, and when I tried to telnet into smtp.balance.org on port 25 from my network, and send email to johnsmith@healthbiz.com (RCPT TO:johnsmith@healthbiz.com
I think it's because CFDynamics does web hosting for healthbiz.com. So when they are looking up johnsmith@healthbiz.com I think they are consulting their own email servers looking for a valid user, rather than just OK'ing the email address and sending the email to the Exchange virtual SMTP server that corresponds to healthbiz.com.
The MX record for healthbiz.com is set up correctly and works just fine... but I think there must be some internal communication problem at CFDynamics.
Thanks, that helps, I was thinking that both sites were using the same domain. My guess is that in fixing your eariler NDR loop problem created the problem. Were you working on both servers or just the local Exchange? The first step is to fiigure out which server is causing your NDR. Check with message tracking, is the remote server Exchange also? Do you have access to it for management?
balance.org is not a Windows Server / Active Directory domain. It's just a website/email domain that they use for a separate business. The website and email hosting for balance.org is done by a company called CFDynamics. The website hosting for healthbiz.com is also done by CFDynamics.
I contacted their support and they said it's a problem on Healthbiz's end.
They replied:
"Our name servers list healthbiz.com but SMTP is pointed to an IP outside our netblock. When searching for mail for that domain our name servers are going to answer and push to the server that our DNS has. We are authoritative for DNS for healthbiz.com so the requests are going to come here but the issue is still with their server. I did a dns report on dnsstuff.com and we are not reporting anything that is naming cfdynamics.com as responsible for mail."
But what this does not explain is why I get the "550 User johnsmith@healthbiz.com not found" error when I telnet to their SMTP server (via telnet smtp.balance.org 25) and do a RCPT TO:johnsmith@healthbiz.com
balance.org is not a Windows Server / Active Directory domain. It's just a website/email domain
Forget about web/dns issues, it's not that, what exactly "email domain" handles mail for all the domains? Is it just one server, or more?
Is Exchange on the edge or do you have gateways or hosted scanning sending to your Exchange?
Have you checked any lockdown stuff on connectors in ESM?
Healthbiz is a small office that is on a small (~20 computers total) LAN, with a T1 Internet connection and static IP address. They are running a Windows Server 2003 server with Exchange Server 2003 SP2 running on it. It's a standalone server (backend and frontend), on the LAN, behind a firewall.
There's no hosted antivirus/antispam filtering. Ports 25 and 110 and 443 are all forwarded to the Exchange server. MX records are set up on the DNS server for healthbiz.com to point to their static IP address.
The web hosting for healthbiz.com is done by a company called CFDynamics (actual name), on their web server.
balance.org is also hosted by CFDynamics. They do both the web hosting and POP3/SMTP hosting for balance.org. balance.org is completely separate from the Healthbiz LAN. The only way they are connected is that CFDynamics hosts the website for healthbiz.com and the website + POP3/SMTP for balance.org.
John Smith has a POP3/SMTP account in his Outlook client, running on his computer on the Healthbiz LAN, using pop.balance.org and smtp.balance.org. These two servers correspond to CFDynamics servers.
There are no connectors set up in Exchange. I've checked access/restrictions on the SMTP Virtual Server and nothing is restricted/denied. I even added CFDynamics' SMTP server IP address to the list of servers allowed to relay.
I think what ever you did to fix one problem:
"It created about 40,000 NDRs before I found out the next morning and stopped it. I turned off NDRs and made several other changes to fix that problem. Now after that problem was resolved, this new SMTP Error 550 problem is occurring)."
Looks like an open relay to me and someone put some restrictions in place, which caused another different problem. How mission critical is this, you assigned max points but you have unlimited to assign.
Well also the points assignment is for how difficult I think the question is, and as I have already posted a question for this very issue a couple months ago and got 0 responses on it, and no one has been able to help me, and no web searches turn up any results, I feel this is a difficult question!
This is also important because employees that are doing Balance.org business cannot forward any emails to Healthbiz.com users, so they can't do any work via email that relates the two businesses.
I also initially thought it was the NDR-infinite-loop fix that caused this new problem, but that doesn't explain why CFDynamics' SMTP server returns "550 User johnsmith@healthbiz.com not found." when I try to do a "RCPT TO:johnsmith@healthbiz.com
This occurs from any network... not just Healthbiz.com's network. Why would CFDynamics' SMTP server be doing any user/email address validation (beyond the normal checks to make sure the form matches a valid email address format: whatever@whatever.ext)?
If I telnet into smtp.balance.org from XYZCompany.com then I am taking Healthbiz's network and Exchange server completely out of the equation. Then when I do "RCPT TO:johnsmith@healthbiz.com
As far as I know, a "RCPT TO:" command is not forwarded from one SMTP server to another, to check if the email address actually exists or not. This leads me to believe that CFDynamics' SMTP server sees the "RCPT TO:johnsmith@healthbiz.com
The only way I can see this hapening is that someone at CFD misconfigured their server to accept email for healthbiz.com. Balance.com should be able to accept mail from its users and send to external domains. The only reason I can see that would make this happen is that it thinks it should do something other than just acceps/forward the emails. That is why I am interested to see healthbiz MX's from the balance domain.
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by: sharkbot221984Posted on 2008-12-18 at 10:22:05ID: 23205899
Is there more information in your NDR? It should be something like error 550 5.7.1 or something similar, that will help target the specific 550 error.
During the changes you made did you disable your POP3 protocols for the users mailboxes? Are there any users listed as being denied access in the access tab -> connection for your SMTP or POP3 virtual servers? Just throwing out some ideas to check....