How to add 'i=' tag in DKIM signature (opendkim)

Question

I would like to add the i, Identity — the identity of the signer — in email address format

Can you help me?

/etc/opendkim.conf contains:

KeyTable                refile:/var/lib/dkimkeys/keyTable
SigningTable            refile:/var/lib/dkimkeys/signingTable
OversignHeaders         From

/var/lib/dkimkeys/signingTable contains:

*.mydomain.com selector._domainkey.mydomain.com

I would like to add i= tag in email siganture.

What actions should I take?

Thanks

Answer 1

According to the documentation, it is possible to do this by adding a second field to your SigningTable entry.

sub.mydomain.com    selector._domainkey.mydomain.com:%
*.mydomain.com      selector._domainkey.mydomain.com:i-tag-value

Either one of those will work. The % will be replaced by the sender's domain in the From: header.