Hi,
I'm using RH6.2 as a mail server. I've already installed and configured sendmail as an MTA and qpopper as pop-3 server.
When i send an email to any user on the server, message is returned back with an error message that the host is unknown.Although i can ping the server by its name.
How can i solve it ?

Sendmail uses DNS (local, network) to resolve MX records for each host its sposed to transfer mail to.

U can perform the same in nslookup to see if it works:
$ nslookup
> set type=mx
> sendmail.org
-Server:
-Address: 123.45.67.8
-sendmail.org preference=20, mail exchanger=mail1.reference.com
-mail1.reference.com inet address=206.171.3.24

u see that even the address may me someone@sendmail.org, the mail will be delivered in real to mail1.reference.com, cuz the MX record specifiy so.

If the MTA cant find the MX record (or MX with other priority) it cant deliver.

Make sure the MX records are available and use the MTA's debug option for more info.

Hi..


This is some problem in ur sendmail confifuration only

First try manually by running sendmail with -bt

sendmail -bt

then give the ruleset name and give some valid email id and check the floww

Example

sendmail -bt
> 0 sidiqu@yahoo.com

Check the rule sets .


Pls give the output so we can analyse

Siddiqu.T

something important to note. That when i type
#nslookup
the following statement appears:

*** Can't find server name for address "some address" :
Non-existent host/domain
*** Default servers are not available

1. check if uve got a working connection to ure ISP
2. check if u entered the correct DNS servers in /etc/resolv.conf and that is working correct

{3a. check if the host/domain/IP is correct, not in the IANA reserved LAN ranges.
3b. check if the host/domain/IP resolves correct with traceroute
3c. check who -should- be the authoritative DNS server for the domain
3d. check -if- it has been up/hosted/added/propagated.}

4. victimize guilty adm/op with prodding iron for being lazy, incompetent, and not RTM'ing in general :-]