Postfix don't sign all mails with DKIM-Signature

Question

I have postfix and opendkim working on my server(Ubuntu 16.04), but postfix do not sign all mails with dkim.

If I send a mail from server with:

echo "test email" | sendmail [email protected]

I have a response that says DKIM check: pass because the mail has DKIM-Signature. I was trying send mails to my gmail account by this method and the mails has a DKIM-Signature too.

But when I try to send mails using Thunderbird or something similar the mails has no DKIM-Signature.

The server only has one domain and the next configurations:

/etc/postfix/main.cf:

[...]
milter_default_action = accept
milter_protocol = 2
smtpd_milters = inet:localhost:8891
non_smtpd_milters = inet:localhost:8891

/etc/opendkim.conf:

[...]
SOCKET              inet:8891@localhost
UserID              opendkim
KeyTable            /etc/opendkim/key.table
SigningTable        refile:/etc/opendkim/signing.table

/etc/opendkim/key.table:

example.com example.com:default:/etc/dkimkeys/dkim.key

/etc/opendkim/signing.table:

*@example.com example.com

I was looking on mail.log, mail.err and syslog but I don't see anything related, neither errors.

I'm checking different configurations, I can send DKIM-signed mails form server with sendmail using different configurations but I still can't send mails signed with DKIM with Thunderbird... :(

Any Idea? Any place to look?

MdeMoUcH MdeMoUcH · Accepted Answer · 2018-04-30T07:01:57

Ok, I found the problem.

In some sites they say that its necesary put the next line in /etc/postfix/master.cf for avoid problems:

-o receive_override_options=no_header_body_checks,no_unknown_recipient_checks,no_milters

But its wrong, that line makes the mails didn't signed.

In /etc/postfix/master.cf we can uncomment the next line to get working the port 587:

submission inet n       -       y       -       -       smtpd

Postfix don't sign all mails with DKIM-Signature

1 Answers