📦 Installation Command
apt install opendkim opendkim-tools
OpenDKIM Port & Email Authentication Setup
opendkim systemctl: opendkimDKIM signing and verification daemon for email authentication.
🔌 Default Port
8891
tcp
Milter socket (or unix socket)
⚙️ Configuration Files
/etc/opendkim.conf/etc/opendkim/KeyTable/etc/opendkim/SigningTable/etc/opendkim/TrustedHosts
📂 Default Directories
- config:
/etc/opendkim.conf - keys:
/etc/opendkim/keys - logs:
/var/log/mail.log - socket:
/var/spool/postfix/opendkim/opendkim.sock
🔐 Default Credentials
Username:N/A
Password:N/A
💡 No user auth - works as milter for Postfix
📌 Dependencies
⚠️ Conflicts
✅ Works With
🛡️ Security Notes
Secure key permissions (0600), rotate keys periodically, monitor signing failures
❓ Frequently Asked Questions
What port does OpenDKIM use?
OpenDKIM uses port 8891 by default for the milter interface.
What is DKIM?
DKIM (DomainKeys Identified Mail) signs emails cryptographically to verify sender authenticity.
Where is OpenDKIM config?
Config at /etc/opendkim.conf with keys in /etc/opendkim/keys/.