How To Generate Dkim Public Key
- Generate Dkim Record
- Create Dkim Keys
- Check Dkim Record
- Create Dkim
- How To Generate Dkim Public Key Signature
- Next you’ll use an online wizard to create the DKIM public / private key pairing and the policy record. The ‘public’ key is a key that will be placed in your public-facing DNS record along.
- STEP 3: Create a public and private key pair Use an online wizard or your mail server’s own key generator to create the DKIM public/private key pairing and the policy record. The public key will be placed in your public-facing DNS record. The private key is installed on the MTA/Email sending system(s). You can also generate your own using.
DKIM (DomainKeys Identified Mail) is a method of signing electronic emails using public-private key. DKIM is used by receiving mail server for identifying email, that they are sent by authorized mail servers. It also minimizes the possibility of getting emails SPAM.
This tutorial will provide you a quick and easy way to set up DomainKeys with your POSTFIX running on CentOS and RHEL systems.
DKIM Wizard This wizard will allow you to easily create a public and private key pair to be used for DomainKeys and DKIM signing within PowerMTA™. The key pair will be used for both DomainKeys and DKIM signing.Policy records are no longer included as they are part of the deprecated DomainKeys, and not DKIM. Domain name of the 'From:' header address, not the SMTP 'MAIL FROM'. DKIM record generator is an online tool to create DKIM DNS record to protect your domain from email scam and phishing.
How DKIM Works ?
When we configured DKIM on sending servers. First, we generated a public/private key pair for signing outgoing messages. The public key is configured as TXT record on a domains name server, and the private key is configured in the outbound email server. When an email is sent by an authorized user of the email server, the server uses the stored private key to generate a digital signature of the message, which is inserted in the message as a header, and the email is sent as normal.
Step 1 – Install DKIM-milter
First make sure you have enabled EPEL repository in your system. After that install dkim-milter package using following command.
Step 2 – Generate Key Pair
Now create DKIM key pair using dkim-genkey command line utility provided by dkim-milter package. For this tutorial we are using domain name “example.com”, Change this name with your actual names.
Above command will generate two files default.private and default.txt. You can created multiple DKIM keys for different-2 domains and configure with your postfix server.
Now set the proper permissions on Keys directory.
Step 3 – Configure OpenDKIM
Edit the Opendkim configuration file and Add/Update following entries in file.
Then edit the domain keys lists setting file /etc/opendkim/KeyTable and add following entry.
After that edit /etc/opendkim/SigningTable file and update following entry.
And edit /etc/opendkim/TrustedHosts file and update following entry.
Step 4 – Configure Postfix
Now edit POSTFIX configuration file /etc/postfix/main.cf and add following values at the end of file
finally start DKIM service using following command
Step 5 – Configure DNS Entry
After configuring private key in postfix server. there will be another file /etc/opendkim/keys/example.com/default.txt/strong> generated by opendkim-genkey. Edit your DNS zone file and add this as TXT record found in default.txt. In my case this is like below.
Step 6 – Verify DKIM
Stepmania 5 song packs roblox. To verify that DKIM is working properly. Let’s send a test email through command line
In the received email in our mailbox, open the source of the email and search for 'DKIM-Signature'. You will find something like below
This tutorial is available in other languages. Help translate more
Italiano /
- Sign DKIM signature on outgoing emails for new mail domain
Don't know what DKIM is? Check our tutorial here: What is a DKIM DNS record.
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Generate Dkim Record
Don't know where Amavisd config file is? check this tutorial:Locations of configuration and log files of major components.
iRedMail configures Amavisd to sign outgoing emails for the first mail domainyou added during iRedMail installation. If you added new mail domain, youshould update Amavisd config file to sign DKIM signature for it.
Let's say your first mail domain added during iRedMail installation ismydomain.com
, and new mail domain is new_domain.com
, please follow belowsteps to enable DKIM signing for outgoing emails of this domain.
Use existing DKIM key for new mail domain
if you already have a working DKIM and valid DKIM DNS record, it's ok touse this existing DKIM key to sign emails sent by other hosted mail domains.This way, you don't need to ask your customer who owns this new domain to addDKIM DNS record.
- Find below setting in Amavisd config file
amavisd.conf
(find its location on different Linux/BSD distributions):
Add one line in @dkim_signature_options_bysender_maps
, after 'mydomain.com'
line like below:
- Restart Amavisd service.
Generate new DKIM key for new mail domain
If you or your customer prefer to use their own DKIM key, you can generatea new DKIM key and ask your customer to add DKIM DNS record. Refer to ourtutorial to add DKIM DNS record.
Create Dkim Keys
Generate new DKIM key (key length
1024
) for new domain, and set correct file owner and permission- on RHEL/CentOS, the command is
amavisd
, user/group isamavis:amavis
. - on Debian/Ubuntu, the command is
amavisd-new
, user/group isamavis:amavis
. - on FreeBSD, the command is
amavisd
, user/group isvscan:vscan
. - on OpenBSD, the command is
amavisd
, user/group is_vscan:_vscan
.
- on RHEL/CentOS, the command is
Note
- on different Linux/BSD distributions, the command may be
amavisd
- on RHEL/CentOS, you must specify the config file on command line like this:
# amavisd -c /etc/amavisd/amavisd.conf genrsa /var/lib/dkim/new_domain.com.pem
- Not all DNS vendors support 2048-bit key length as TXT type record, so iRedMail generates the key in 1024-bit. If you want to use 2048-bit instead, please specify the key length on command line:
# amavisd -c /etc/amavisd/amavisd.conf genrsa /var/lib/dkim/new_domain.com.pem 2048
- Find below setting in Amavisd config file
amavisd.conf
:
Add one line after above line like below:
- Find below setting in Amavisd config file
amavisd.conf
:
Add one line after 'mydomain.com'
line like below:
- Restart Amavisd service.
Again, don't forget to add DKIM DNS record for this new domain. The value ofDKIM record can be checked with command below:
After added DKIM DNS record, please verify it with command:
Note: DNS vendor usually cache DNS records for 2 hours, so if above commandshows 'invalid' instead of 'pass', you should try again later.
Use one DKIM key for all mail domains
Check Dkim Record
If you want to use one DKIM key for all mail domains, please follow steps below:
- Make sure you have at least one DKIM key configured like below in Amavisd config file (
amavisd.conf
):
- Find parameter
@dkim_signature_options_bysender_maps
, and set it to:
Create Dkim
- Restart Amavisd serivce.
References
- Amavisd official document: Setting up DKIM mail signing and verification
How To Generate Dkim Public Key Signature
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