Redirecting output of 'sendmail -bv' to console

linux_user2011 · 05-03-2011, 06:02 AM

Hi,

I am using RHEL Linux 6.0

When I run 'sendmail -bv', it sends the mail delivery status report as a mail to the root. Is there a way I can redirect this to the console instead of sending as a mail.My requirement is to programatically find the mail host of the recipient for which I thought of using this 'sendmail -bv' command. Is there any other better way to find mail host of the recipient.

Regards,

bathory · 05-03-2011, 07:18 AM

Hi,

Are you sure about this. The command needs also the recipient, so it can produce some output

Quote:

sendmail -bv
Recipient names must be specified

sendmail -bv foo@gmail.com
foo@gmail.com... deliverable: mailer esmtp, host gmail.com., user foo@gmail.com

Maybe you're running postfix, or another mta, whose sendmail binary replacement is not a 100% compatible with sendmail

Regards

linux_user2011 · 05-04-2011, 12:28 AM

Thanks for the reply Bathory!

Now only I found that its postfix sendmail:
[root]# man sendmail
SENDMAIL(1) SENDMAIL(1)

NAME
sendmail - Postfix to Sendmail compatibility interface

And the command I am running is as below:
[root]# sendmail -bv abc@gmail.com
Mail Delivery Status Report will be mailed to <root>.

Is there a way I can redirect the above report to console. My requirement is to find the recipient's mail host programatically and I wanted to make my implementation simple by redirecting the sendmail's output to console and directly reading it from console. How do I do it?

Or is there any other better and simpler way to find out the recipient's mail host? Please advise...

Regards...

bathory · 05-04-2011, 02:37 AM

IMO the output of the original sendmail -bv, is only useful for the mailer part. It allows you to see if the mail is local, if it's going through a relay, or directly via smtp and so on.
The host part says nothing useful. You can find the real smtp host(s) for a domain using dns tools, like dig:

Code:

dig mx gmail.com
<snip>
;; ANSWER SECTION:
gmail.com.              2205    IN      MX      5 gmail-smtp-in.l.google.com.
gmail.com.              2205    IN      MX      10 alt1.gmail-smtp-in.l.google.com.
gmail.com.              2205    IN      MX      20 alt2.gmail-smtp-in.l.google.com.
gmail.com.              2205    IN      MX      30 alt3.gmail-smtp-in.l.google.com.
gmail.com.              2205    IN      MX      40 alt4.gmail-smtp-in.l.google.com.
<snip>

linux_user2011 · 05-05-2011, 01:15 AM

Thanks Bathory,

You said the host part says nothing useful. I just tried the below in my Solaris box:

bash-3.00# sendmail -bv abc@gmail.com
abc@gmail.com... deliverable: mailer esmtp, host gmail.com., user abc@gmail.com

bash-3.00# sendmail -bv abc@hotmail.com
abc@hotmail.com... deliverable: mailer esmtp, host hotmail.com., user abc@hotmai
l.com

bash-3.00# sendmail -bv abc@rediffmail.com
abc@rediffmail.com... deliverable: mailer esmtp, host rediffmail.com., user abc@
rediffmail.com

In all the above examples, the host part is same as the domain with an additional dot at the end. I was thinking that host represents the mail host or the relay host. Or is it just the domain name? Please correct me if I am wrong.

Regards

bathory · 05-05-2011, 03:06 AM

Quote:

I was thinking that host represents the mail host or the relay host.

It is supposed to be the host that will get the mail for that user.
In case you use a smarthost, the mailer part becomes relay and the host is the smarthost

Quote:

sendmail -bv foo@gmail.com
foo@gmail.com... deliverable: mailer relay, host smarthost.domain.com, user foo@gmail.com

Without a smarthost, sendmail uses the host part to do an MX lookup for it in order to find the actual smtp host to deliver the mail
You can take a look at chapter 5.0 of sendmail Cookbook by O'Reilly Media for details.

Regards

linux_user2011 · 05-05-2011, 11:27 PM

I need to get the equivalent of this host in RedHat Linux 6.0. But Linux 6.0 has postfix as its default mail server. I tried using postfix sendmail -bv but its output is different. How can I get the equivalent of host in RHEL Linux 6.0

Regards

bathory · 05-06-2011, 12:25 AM

Quote:

I need to get the equivalent of this host in RedHat Linux 6.0. But Linux 6.0 has postfix as its default mail server.

I was under the impression that RH still uses sendmail as the default mta, but after reading this, looks you're right. If you want, you can switch to sendmail running:

Code:

alternatives --config mta

Anyway you can filter root's mail (through procmail?) and extract the info you want.

linux_user2011 · 05-09-2011, 12:27 AM

I dont have sendmail installed in the box, hence I need to go with postfix sendmail.

Below is the output of sendmail (from Solaris box as I dont have a Linux 4/5 and this Solaris box has sendmail):

On Solaris:
-----------
bash-3.00# sendmail -bv pnet_register@bmc.compnet_register@bmc.com... deliverable: mailer esmtp, host bmc.com., user pnet_register@bmc.com

On Linux
----------
[root@vm-rlnx-rds1203 /]# sendmail -bv pnet_register@bmc.com
Mail Delivery Status Report will be mailed to <root>.
[root@vm-rlnx-rds1203 /]# mail
Heirloom Mail version 12.4 7/29/08. Type ? for help.
"/var/spool/mail/root": 8 messages 1 new
1 Mail Delivery System Thu May 5 11:52 62/2105 "Mail Delivery Status Report"
2 Mail Delivery System Thu May 5 11:54 62/2135 "Mail Delivery Status Report"
3 Mail Delivery System Thu May 5 11:57 62/2077 "Mail Delivery Status Report"
4 Mail Delivery System Mon May 9 10:32 62/2105 "Mail Delivery Status Report"
5 Mail Delivery System Mon May 9 10:32 62/2135 "Mail Delivery Status Report"
6 Mail Delivery System Mon May 9 10:45 62/2143 "Mail Delivery Status Report"
7 Mail Delivery System Mon May 9 10:51 62/2077 "Mail Delivery Status Report"
>N 8 Mail Delivery System Mon May 9 10:51 61/2066 "Mail Delivery Status Report"
& 8
Message 8:
From MAILER-DAEMON Mon May 9 10:51:50 2011
Return-Path: <>
X-Original-To: root@vm-rlnx-rds1203.bmc.com
Delivered-To: root@vm-rlnx-rds1203.bmc.com
Date: Mon, 9 May 2011 10:51:50 +0530 (IST)
From: MAILER-DAEMON@vm-rlnx-rds1203.bmc.com (Mail Delivery System)
Subject: Mail Delivery Status Report
To: root@vm-rlnx-rds1203.bmc.com
Auto-Submitted: auto-replied
Content-Type: multipart/report; report-type=delivery-status;
boundary="029AD162778.1304918510/vm-rlnx-rds1203.bmc.com"
Status: R

Part 1:
Content-Description: Notification
Content-Type: text/plain; charset=us-ascii

This is the mail system at host vm-rlnx-rds1203.bmc.com.

Enclosed is the mail delivery report that you requested.

The mail system

<pnet_register@bmc.com>: delivery via phx-flicker-01.bmc.com[172.24.33.152]:25:
250 2.1.5 Ok

Part 2:
Content-Description: Delivery report
Content-Type: message/delivery-status

Part 3:
Content-Description: Message Headers
Content-Type: text/rfc822-headers

Return-Path: <root@vm-rlnx-rds1203.bmc.com>
Received: by vm-rlnx-rds1203.bmc.com (Postfix, from userid 0)
id 029AD162778; Mon, 9 May 2011 10:51:48 +0530 (IST)
From: root@vm-rlnx-rds1203.bmc.com
Subject: probe
To: pnet_register@bmc.com
Message-Id: <20110509052149.029AD162778@vm-rlnx-rds1203.bmc.com>
Date: Mon, 9 May 2011 10:51:48 +0530 (IST)
&

The sendmail command returned the host as bmc.com. and the postfix output says delivery via phx-flicker-01.bmc.com I was wondering why both are different as I had given the same recipient. I couldnt find the exact equivalent of host from sendmail -bv output in postfis output

Regards

bathory · 05-09-2011, 02:17 AM

Hi,

Quote:

<pnet_register@bmc.com>: delivery via phx-flicker-01.bmc.com[172.24.33.152]:25:
250 2.1.5 Ok

Here is says that it's going to deliver the message through phx-flicker-01.bmc.com (I guess this is a relay host for your box). Most likely the sendmail in Solaris is not configured to use a smarthost (synonym of relayhost for postfix), otherwise it should also mention that (see also my post #6). You can test if you like, by adding in the DS line os sendmail.cf the relayhost, eg.

Code:

DSphx-flicker-01.bmc.com

and run sendmail -bv (do not restart sendmail, otherwise any mail sent during the test, will be forwarded to smarthost)

Also, if you take a look at the example here, you'll see that mail is delivered through mail.cloud9.net, which is the same as the output of dig mx"

Quote:

; <<>> DiG 9.7.3 <<>> mx postfix.org
<snio>
;; ANSWER SECTION:
postfix.org. 86388 IN MX 10 mail.cloud9.net.
<snip>

So once again, the original sendmail does not bother to show the actual MX of the domain. It just outputs the way the mail will be delivered.

lrtward · 05-10-2011, 08:18 AM

Quote:

Originally Posted by linux_user2011

My requirement is to programatically find the mail host of the recipient for which I thought of using this 'sendmail -bv' command. Is there any other better way to find mail host of the recipient.

When you say "the mail host" do you mean the destination host where the mail accounts are housed, or the mail exchange host -- the one that accepts mail for a domain? It's probably going to be impossible to find the server name where the mail accounts are actually housed, but it should be pretty easy to find the MX hosts.

There can be multiple MX hosts:

Code:

]# dig mx hotmail.com

; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_4.2 <<>> mx hotmail.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53333
;; flags: qr aa; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 24

;; QUESTION SECTION:
;hotmail.com.                   IN      MX

;; ANSWER SECTION:
hotmail.com.            3600    IN      MX      5 mx4.hotmail.com.
hotmail.com.            3600    IN      MX      5 mx1.hotmail.com.
hotmail.com.            3600    IN      MX      5 mx2.hotmail.com.
hotmail.com.            3600    IN      MX      5 mx3.hotmail.com.

You can get the list of all MX hosts by doing something like this:

Code:

dig mx domain.com | grep MX | awk '{ print $NF }' | grep -v MX

There are probably more elegant ways to do it but this should work.

linux_user2011 · 05-11-2011, 04:02 AM

I am actually modifying a script that works on Solaris to work on Linux. Below is the part of the script where we are getting mail host:

sendmail -bv pnet_register@bmc.com 2>&1 > /tmp/output
MAILHOST=`cat /tmp/output | grep "," | awk -F, '{print $2}' | awk '{print $2}'`

(here we get bmc.com. as the MAILHOST)

I think it is the one that accepts mail for a domain.

For converting it to work on linux, if I use the below command as suggested by you, I get the below output:

[root@vm-rlnx-rds1203 ~]# dig mx bmc.com | grep MX | awk '{ print $NF }' | grep -v MX
phx-flicker-01.bmc.com.
hou-flicker-01.bmc.com.

I wonder whether what I am doing is correct. If yes, they why on Solaris I am getting bmc.com. and on Linux phx-flicker-01.bmc.com. and
hou-flicker-01.bmc.com.

Regards

bathory · 05-11-2011, 04:59 AM

Hi,

As I've already told you, the original sendmail -bv, just outputs how the mail will be delivered (local, by relay, by smtp). It does not do a MX lookup to find the actual MX host of the recipient.The postfix sendmail -bv on the other side, simulates the whole delivery process, so it does the MX lookup and also connects to the MX host.
BTW, if you use dig in Solaris, you'll also get the same results for MX.

Regards