sendmail 8.9.3 - SMTP - mail issues

[Vinod Subramanian]

I have checked my sendmail configuration (sendmail -v user@host.domain.com), sendmail.cf, aliases file, everything looks ok. I am getting email notifications from this system through sendmail.

I am getting a mail message from mailer-daemon about a failed delivery repeatedly. I am not able to figure out what is causing this mail to be delivered repeatedly. Everything was working fine. I only change done was sendmail was restarted around 2 hrs prior to the getting the first mail from mailer-daemon.

I have alias set for mailer-daemon to Unix.Sysadmins@mydom.com

nslookup on test1.mydom.com returns the ip-address of the system. resolv.conf has the correct entry for the domain and ip address of nameservers. nsswitch.conf has dns entry followed by entry for files. I also tried putting files before dns with no change in result.

I have sent mail directly to both root@test1.mydom.com and Unix.Sysadmins@mydom.com and it gets delivered to the admin inbox. I also see the entries in /var/adm/syslog/mail.log when that happens, but for the mailed getting bounced I don't see any entries in the mail.log file.

Any help will be appreciated.


Error message in the mail from the mailer-daemon
----------------------------------

From: Mail Delivery Subsystem [mailto:MAILER-DAEMON@test1.mydom.com]
Sent: Tuesday, July 29, 2003 1:16 AM
To: root@test1.mydom.com
Subject: Returned mail: Data format error


The original message was received at Tue, 29 Jul 2003 01:16:03 -0400 (EDT)
from root@localhost

----- The following addresses had permanent fatal errors -----
Unix.Sysadmins@mydom.com
(expanded from: root)

----- Transcript of session follows -----
>>> MAIL From: SIZE=382
<<< 553 5.1.8 ... Domain of sender address root@test1.mydom.com does not exist
501 Unix.Sysadmins@mydom.com... Data format error

[Steven E. Protter · Accepted solution]

I'm not sure if the data at the bottom is an example, because test1.mydom.com does exist and is a valid domain.

I shall assume it is.

Your mail seems to be rejected because DNS is being checked by the receiving smtp server prior to accepting the mail.


aol does it.

I do it.

To get mail onto those servers you need to have your mail server be part of a valid domain.

A few ways to do that.

1) change hostname. hpweb becomes hpweb.mydomain.com

That will work unless your domain name exceeds 8 characters. Then HP-UX will get yucky on you and not work right.

2) Change the Dj directive in sendmail.cf

#Dj ...

becomes

Djmydomain.com

save sendmail.cf

/sbin/init.d/sendmail stop
/sbin/init.d/sendmail start

Before you start messing around though, do an upgraded diagnostic test.

sendmail -v -d8.99 -d38.99 someone@aol.com

type some text

.


You'll get more.

Try it out on a coupole of domains and see if some mail is accepted and other mail not.

SEP

[Vinod Subramanian]

Steve,
Thanks for the response. The message at the bottom my question is one I get in the bounced messages. You are right in assuming that mydom.com is a valid domain.

I tried sendmail -v -d8.99 -d38.99
with different addresses. I don't seem to get any error messages.

From looking at the /var/adm/syslog/mail.log it doesn't look like the the bounced mail is being sent continuosly from the test1.mydom.com server itself.

I tried changing the mailer-daemon entry in the aliases to point to /dev/null, that didn't work either. I have also changed the Dj option in sendmail.cf and restarted sendmail, still keep getting those emails.

[Steven E. Protter]

At this point, getting no errors from the sendmail command, I'd take a look at the DNS record for the domain.

Sounds like there is something circular going on there.

If however you are using the DS directive there is another possibility.

I got some very similar messages while relaying off our Symmantec firewall. After I convined management that we should look at the firewall, it turns out we needed to patch Synmmantec's smtp relay functionality.

Thats why you get no error, because the smtp relay server accepts the mail. Fortuneately if you are using relay you have enabled bad messages to bounce back.

I'd be interested to see if the mail.log file produces anything interesting.

Also, the DNS record for the domain might be good bedtime reading. Yeah, I know thats pretty bad, but I've finished all the Harry Potter books. As a friend said, you've got a great name, all you need to do is lose an r.

SEP

[Joerg Hinz]

Another way to solve that problem without working on DNS is simply turn off sendmails behaviour to verify sender addresses:

If you use a sendmail.mc-file for generation of the sendmail.cf add those lines above the MAILER-Definitions:

FEATURE(accept_unqualified_senders)dnl
FEATURE(accept_unresolvable_domains)dnl

If you use the MSP beside the MTA put

FEATURE(nocanonify)dnl
define(`confDIRECT_SUBMISSION_MODIFIERS',`C')dnl

into the submit.mc.

The regenerate both sendmail.cf and submit.cf and restart sm-mta and sm-msp (or just sendmail).

If you now send mail sendmail should take it whatever the domain is.

NOTE: You should not use that feature on internet MTAs to prevent spam using fake sender-addresses.

Joerg