450 MX Lookup Failure, 450 Host Down and 550 Host Unknown Errors
(Last modified: 30Jan2004)
This document (10009322) is provided subject to the disclaimer at the end of this document.
fact
Novell GroupWise 5.5
Novell GroupWise 6.0
Novell GroupWise Internet Agent
symptom
Error: "450 Host down"
Error: "450 MX Lookup Failure"
Error: "550 Host unknown"
Errors show up in GWIA Log File or on the GWIA screen
Error sending outbound email
cause
A "450 MX Record Lookup Failure" message means that the SMTP or GWIA Gateway cannot find or connect with the Domain Name Server.
Possible reasons for 450 error:
1. IP address to DNS has changed. If this is the case update the RESOLV.CFG
2. IP filtering has been added to the routers so the gateway cannot see the DNS machine.
3. Bad network card (NIC).
4. TCP/IP is not bound to the network card.
5. Bad network cabling.
6. named is not running on the DNS machine.
7. The DNS machine is down.
8. The specific site your sending email may be down. If you can send email to other locations, then in most cases all your GWIA/DNS settings are fine. Try sending the email again later to see if their site is running. A good test is loading ping at the server console and try pinging the site your trying to send email to.
9. The ISP which is hosting the DNS may have the wrong entry for the MX record.
fix
Make sure you have a default route correctly configured. See Configuring a Default Route.
Check the RESOLV.CFG file for correct configuration. By default, this file is located in the SYS:\ETC directory. Make sure it is spelled correctly.
The contents of the RESOLV.CFG file should be in all lowercase letters with the following format:
domain <your_domain_name>
nameserver <ip_address>
nameserver <ip_address>
nameserver <ip_address>
NOTE: In some cases changing the order of the nameservers, will resolve this issue. That indicates a problem with the nameserver that was listed first in the list.
If you are using NAT on your server, add the following set command to the autoexec.ncf:
SET NAT DYNAMIC MODE TO PASS THRU=ON
If you are not hosting your own DNS, contact the ISP that is hosting your DNS can be sure that he has the correct MX record for your site.
cause
TCP/IP out of date.
fix
Make sure the server is fully patched.
cause
/mh switch is missing from gwia.cfg.
fix
Add the /mh-"Smart Mail Host IP Address" to the gwia.cfg file.
Some users do not want to resolve DNS for outgoing email. In this case they must send all the outgoing internet email to a Smart Mail Host. This can also be done by adding the correct IP address to the Relay Host for Outbound Messages in the details of the GWIA object under SMTP/MIME Settings.
cause
/mh switch is incorrect from gwia.cfg
fix
If the /mh switch has been added to the gwia.cfg, or name of the Relay Host for Outbound Messages in the details of the GWIA object under SMTP/MIME Settings in NWADMN, however the host name is incorrect or that host is not running mail services.
cause
Filtering has been added to the routers so the gateway cannot see the DNS machine.
fix
Remove the filters that block the DNS machine.
document
| Document Title: | 450 MX Lookup Failure, 450 Host Down and 550 Host Unknown Errors |
| Document ID: | 10009322 |
| Solution ID: | 1.0.889432.2061234 |
| Creation Date: | 18Mar1999 |
| Modified Date: | 30Jan2004 |
| Novell Product Class: | Connectivity Products Groupware NetWare Novell BorderManager Services |
disclaimer
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