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How to enable DKIM in cPanel server.

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DomainKeys Identified Mail (DKIM) lets an organization take responsibility for a message while it is in transit and one can use this to prevent from getting blacklisted by the free email providers like Yahoo, MSN and Google. DKIM can increase the mail authenticity.

cPanel does not have an interface to enable DKIM like we have for SPF and Domain Keys. cPanel is still working on it for getting it implemented. However we can enable it manually by following the below steps.

Check if exim is compiled with DKIM support enabled.

root@server # /usr/sbin/exim -dd 2>&1 | grep Experimental_DKIM

Support for: crypteq iconv() IPv6 PAM Perl OpenSSL Content_Scanning Old_Demime Experimental_SPF Experimental_SRS
Experimental_DomainKeys Experimental_DKIM

Generate the SSL keys

cd /usr/local/cpanel/etc/exim

openssl genrsa -out dkim.key 1024
openssl rsa -in dkim.key -out dkim.public -pubout -outform PEM

You will find two keys, dkim.key & dkim.public

Open dkim.public and copy the contents excluding the –Begin– and –End– section. This is your DKIM key. Now open exim configuration file and append the below entries under the section ‘remote_smtp’

Sample file: vi /etc/exim.conf

——————————-

remote_smtp:
driver = smtp
#
dkim_domain=your_domain_name.com
dkim_selector=mail
dkim_private_key=/usr/local/cpanel/etc/exim/dkim.key #path to the dkim.key key.
interface = ${if exists {/etc/mailips}{${lookup{$sender_address_domain}lsearch*{/etc/mailips}{$value}{}}}{}}
helo_data = ${if exists {/etc/mailhelo}{${lookup{$sender_address_domain}lsearch*{/etc/mailhelo}{$value}{$primary_hostname}}}
{$primary_hostname}}

————————–

Now on WHM, open DNS editor for the particular domain and add the TXT entry with DKIM key like below.

————————–

mail._domainkey.domain_name.com. IN TXT "v=DKIM1; g=*; k=rsa;p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDv4PSEM9P
cxlI2tRojAUQ9hpRQ0Zj/XM4SK08/Drhm/CaspJAKZF9rZDAw18TrfuXeRgsMWAdS2vJ4Oa/kXqX0NM2eBJcmasu4GeNXANmXvC1umz+8mC6r
EPlE/Ucau4tmAHOZL0HJ9IDd/PIxoTkeTm3mjGeqvKBLbdvVIDXbcQIDAQAB"

————————–

Here p=the_key_you_have_copied_from_dkim.public

Restart exim and named services.

/scripts/restartsrv exim

/scripts/restartsrv named

To check whether DKIM is setup properly, send a mail to dkimtest@atmail.org , if setup properly, you will get a reply like below ,else a failure message.

—————————————————-

Subject:    AutoReply from dkimtest@atmail.org

From:    spftest@your_domain_name.com

Date:    Sun, May 23, 2010 1:27 am

To:    spftest@your_domain_name.com

*** DKIM TEST SUCCESSFUL ***

—————————————————–

Or you can also test from http://www.brandonchecketts.com/emailtest.php

27 Comments to “How to enable DKIM in cPanel server.”

Doug Smith July 17, 2010 at 12:14 am
Thanks for the great writeup. I've been looking all over for how to get DKIM working on cpanel and your tutorial was perfect.

Will this setup survive cpanel/whm updates or does some of it need to be redone each time?

Reply
Doug Smith July 17, 2010 at 1:33 am
I guess I spoke too soon. I'm not seeing the DKIM header added to outgoing messages. I already had domainkeys set up and that header is present. I suspect the differences in my exim.conf from the domainkeys configuration is causing it not to work but I haven't been able to nail down why yet.

Reply
- Faheem July 17, 2010 at 1:51 am
  This should survive even after a WHM update I believe, since configurations are not re-written while updating.
  
  I was able to figure out the DKIM keys on mail header. Can you send a test mail to gmail and verify the header? Hope you have entered the configuration properly.
  
  Reply
WAN IP Address September 7, 2010 at 3:22 pm
Thx man, this is great tutorial, DKIM works perfect on my server

I can see DKIM keys on mail headers

Reply
DKIM'r October 12, 2010 at 5:05 pm
I used the following because i have multiple domains which send using their unique IP's:

dkim_domain=$sender_address_domain

dkim_selector=mail

dkim_private_key=/usr/local/cpanel/etc/exim/dkim.key

I had to disable domain keys on each cPanel account and manually enter the dkim dns settings in WHM:

mail._domainkey 14400 IN TXT "v=DKIM1; g=*; k=rsa; p=(whaterver your dkim.public contents were with no brackets);"

It seems to be working!

I can't believe the tools at cPanel are saying "Well we may just end up giving you one or the other" for the last what couple of years?? and we could already easily enable one of the two ourselves with this little tweak?

Thanks

Reply
- Faheem October 13, 2010 at 1:05 am
  @DKIM'r Thanks for your note I will modify the post and put your note to enable DKIM for multiple domains.
  
  I believe there are some licensing issues with DKIM that is keeping cPanel away from enabling this by default. Glad they cPanel exim is compiled to support DKIM by default .
  
  Reply
[ETA 11.32] Add support for DKIM ("DomainKeys Identified Mail") - Page 9 - cPanel Forums November 16, 2010 at 7:06 pm
[...] for DKIM ("DomainKeys Identified Mail") Well do you guys think this should work How to enable DKIM in cPanel server. | techinterplay __________________ Vinayak Sharma Vinsar.Net – Quality WebHosting Services at Economical Price [...]

Reply
Miguel December 8, 2010 at 9:14 am
I have done all steps (to single and after to multiple domains) and mails are not signed, what can i do? i dont see any error on /var/log/exim_mainlog :/

Reply
Faheem December 9, 2010 at 9:30 pm
@Miguel, I have replied your mail.

Reply
kamal December 28, 2010 at 5:55 am
hi

I set up everything but when I send email in exim log file I get

2010-12-27 22:19:32 1PXI8R-0002PJ-74 DKIM: signing failed (RC -101)

and no dkim attach to my email where is the poroblems

Reply
- Faheem December 30, 2010 at 7:46 pm
  @kamal not sure, would need to check into the configurations, just email it to techinterplay at gmail.com
  
  Reply
Andre January 10, 2011 at 11:05 pm
The best DKIM online tutorial. One question…

Inside exim.conf: "dkim_domain=your_domain_name.com"

That's for 1 domain only.

What would put in if I also want to add dkim for: your_domain_name_2.com

Can you please kindly provide the copy-paste solution.

Thank you so much.

Reply
harith January 12, 2011 at 6:14 am
how to add dkim for multiple website using the above steps..

Reply
Namski January 14, 2011 at 7:53 pm
I did follow step by step as the tut, but can't get it working. The DKIM header never show up? Do I have to wait for the DNS to up propagated world wide or something?

Reply
Rudi March 11, 2011 at 7:55 pm
Thanx for this great tip.

From what I understand, this will install DKIM on a single domain.

How do I configure the server if it's a shared hosting server (i.e. there are about 200 domains on the server) for each domain to have DKIM support?

Reply
Steve April 23, 2011 at 11:04 am
Followed the instructions above on cpanel… I removed domain keys from all sites, then followed the above instructions. I used the dkim_domain=$sender_address_domain for multiple domains, restarted exim and named and nothing is being signed.

I then went in and change dkim_domain=mysite.com…. restarted both again… sent an email and nothing…

Everything went smooth, however, nothing is getting signed… tested by sending email to gmail as well and it auto goes to the spam folder with no sig…

Please help… really need to get this implemented for all domains, but would be happy if just one works for now…

Anyone have any ideas!?

Reply
Steve April 23, 2011 at 11:23 am
Scratch that… now it seems to be sending the signature.. perhaps dns had to update, but is showing :

result = fail

Details: body has been altered

when using the http://www.brandonchecketts.com/emailtest.php test… what does that mean?

Reply
Steve April 24, 2011 at 11:31 am
Just spoke to cpanel and the changes made in exim.conf will be overwritten if there is an upgrade. You cannot edit in whm exim advanced editor because it does not support changing the remote_smtp transport… cpanel gave me this response :

1. Create a file named /scripts/posteximup

2. Give it permissions of 0700

3. Place code inside that file that will change the remote_smtp transport

to the one you wish to use. This can be shell scripting, or perl, or any other

language you'd like.

The "posteximup" hook is documented here:

Service script hooks

cPanel & WHM Script Hooks

Basically it just says this:

~~~~~~~~~~~~~~~~~~~~~~~~~~

Runs after Exim updates

(post /scripts/eximup)

~~~~~~~~~~~~~~~~~~~~~~~~~~

If anyone would like to tacke that please do so… it is over my head and laguages I am not familiar with… it would be nice to include this if it will just be wiped on an exim upgrade…

Reply
- Faheem April 26, 2011 at 7:08 pm
  Setting up an attribute for exim.conf will do the job make it immutable and it will remain unmodified for ever.
  
  chattr +i /etc/exim.conf
  
  Reply
Faheem April 25, 2011 at 6:10 am
Steve, can you mail me your exim.conf and TXT DNS record to techinterplay [at] gmail.com ? I would like to have a look.

Reply
Faheem April 25, 2011 at 6:15 am
Steve, http://www.brandonchecketts.com/emailtest.php will display you a randomly generated email address to which you can send from for which DKIM is enabled and by clicking on "View Results: button will give you the test results Did you get it working?

Reply
Mike McKoy April 27, 2011 at 1:22 pm
Hey guys… first I want to thank everyone for the really awesome tutorial.

I'm having some trouble with the 2rd step. When I open the EXIM advanced configuration file via WHM I cannot save the information in the file. I get an error stating driver SMTP not found.

This is the information i'm trying to copy. Thoughts?

`remote_smtp:

driver = smtp

#

dkim_domain=your_domain_name.com

dkim_selector=mail

dkim_private_key=/usr/local/cpanel/etc/exim/dkim.key #path to the dkim.key key.

interface = ${if exists {/etc/mailips}{${lookup{$sender_address_domain}lsearch*{/etc/mailips}{$value}{}}}{}}

helo_data = ${if exists {/etc/mailhelo}{${lookup{$sender_address_domain}lsearch*{/etc/mailhelo}{$value}{$primary_hostname}}}

{$primary_hostname}}

`

Reply
Mike McKoy April 27, 2011 at 1:33 pm
^^^ please ignore the comment above. I was able to get around the smtp issue. I was saving the configuration changes in the wrong place.

However i'm now getting the error:

Error message from syntax check:

2011-04-26 22:29:18 Exim configuration error in line 1144 of /etc/exim.conf.buildtest.work.lQ9WiSdEkvkwLLEA:

option setting expected: {$primary_hostname}}

Any thoughts? this is what I plugged in. I'm trying to enable this to work with multiple domains.

remote_smtp:

driver = smtp

#

dkim_domain=$sender_address_domain

dkim_selector=mail

dkim_private_key=/usr/local/cpanel/etc/exim/dkim.key #path to the dkim.key key.

interface = ${if exists {/etc/mailips}{${lookup{$sender_address_domain}lsearch*{/etc/mailips}{$value}{}}}{}}

helo_data = ${if exists {/etc/mailhelo}{${lookup{$sender_address_domain}lsearch*{/etc/mailhelo}{$value}{$primary_hostname}}}

{$primary_hostname}}

Reply
- Faheem April 27, 2011 at 8:51 pm
  Mike, can I have the line numbers for the pasted lines? Also dkim_domain=example.com
  where example.com is the domain name for which DKIM has to be enabled.
  
  Reply
Mike McKoy April 27, 2011 at 11:44 pm
Faheem,

is this solution only for a single site? I havee a dedicated machine with 8 sites on it. If I can only use one site this is no good.

Also, please look at my second example not the first. I need an answer to the error I was getting in the second.

Reply
Yousaf August 4, 2011 at 10:01 am
I try to add this at all. I done every thing very well but the test fails what to do? I have server with cPanel Centos OS
Thank YOu

Reply
Ola November 21, 2011 at 7:33 am
The strangest thing.. And I’m pretty sure that the solution is fairly simple..

I’m trying to install DKIM for one of my domain hosted on a dedicated server with cPanel WHM..

I’m following this tutorial (http://techinterplay.com/enabled-dkim-cpanel-server.html) but the DKIM test is unsuccessful..

Since I host the email for this domain name at Google Apps, I make the DKIM test from a simple php code by using the php mail() function

What’s causing the failure of the DKIM? Thanks for your help!!

Reply