POP3 Clients Relaying Denied

[sim]

My outlook clients in one of my subsidiary company uses
pop3 & smtp to send thier email. When they try to send an
email outside our organization such as (e-mail address removed)
they will get an NDR that says:

Your message did not reach some or all of the intended
recipients.
Subject:
Sent: 3/10/2004 2:19 PM
The following recipient(s) could not be reached:
'(e-mail address removed)' on 3/10/2004 2:19 PM
550 5.7.1 <[email protected]>... Relaying denied. IP name
lookup failed [203.131.105.140]

 

[Guest]

The key is in the 'relaying denied' report - basically one of the smtp servers the message is passing through is rejecting it, probably because the host name being used doesn't match the DNS lookup that the mail server does. So, for example: if I send a mail from '(e-mail address removed)' but the IP address resolves to 'yourhouse.com' then a properly set-up server should refuse to 'relay' and return the message. This is an anti-spam feature to stop people hiding the origination of a message and using your smtp server to send their mail

Look at the host names, reply addresses and your dns/reverse dns setup and make sure its all consistent. If so, check with your ISP

Reg

 

[Jeff Stephenson [MSFT]]

See
http://office.microsoft.com/assistance/preview.aspx?AssetID=HA011128331033
for information on this.