help with sendmail error: reject=550 5.7.1

[K.C. Chan]

All,
I have a sendmail server running on private network 10.10.?.? (which is nat to pub ip on the firewall). I have the firewall serving up dhcp on 191.168.?.?. I am seeing this error on the log file. As far as I know, the error points to improper dns configuration. But when I check dns for A record and PTR record for this client(Using private dns offcourse), it resolves properly. What gives? Could someone shed some light onto this? Thanks. Here's the msg:
"sendmail[23392]: h4QIWwN23392: ruleset=check_rcpt, arg1=, relay=[192.168.240.11], reject=550 5.7.1 ... Relaying denied. IP name lookup failed [192.168.240.11]"

[Jerome Henry · Accepted solution]

Hi,
It seems that you have 2 problems : "Ip name lookup failed" and "relaying denied". It's much possible that the first rely on the second.
Basically sendmail doesn't relay mail form other machine than localhost to avoid spam. It's easy to fix, by adding in /etc:mail/access file name of machines you relay and their IP.
Then your machine will relay, and thus allow Ip name lookup.
Read RedHat tips on that at :
http://www.europe.redhat.com/documentation/rhl7.3/rhl-rg-en-7.3/s1-email-sendmail.php3
hope this helps.
J

[Steven E. Protter]

There are two ways to get mail onto the Internet.

One is with a direct connectoin and proper DNS resolution, your mail server can figure out where the mail is supposed to go, local or internet, contact the correct server based on the mx record and deliver the mail.

The other is to use a mail relay server. If the mail relay server does not allow you to relay mail you can get this eror. Mail relay is set up with a DS record in /etc/sendmail.cf


example.
DS
[192.168.0.1]

If the server in question was used to send mail to my mail server, I would have taken the following steps:

1) Add the ip addresss an erorr code and message to my access file

ip_addy 550 No spam allowed.

Then I would have rebuilt the hash databases with the script I'm attaching.

That gets all mail from that source bounced with a message. Quide mean, but quite deserving if its from a spammer.

If you control the mail relay server you need to have entries like this for authorized mail relay IP's


192.168.0.40 RELAY
192.168.0.41 RELAY
192.168.0.2 RELAY


Just little information that should help you track this down.

Here is a little diagnostic that might help you gather more information. Its only good on the Linux server.

sendmail -v d38 d9 some@mail.com

You type that command, a line of text then

Then type a dot
.

You will get pinpoint diagnostic information.

Good luck.

SEP

[K.C. Chan]

This is resolved. Thanks all.