What could be the problem with DKIM?

Question

SPF

On Centos 6, Postfix, OpenDKIM server. Emails on Gmail end up in spam, here are the headers:

Received: from u-on.ru (u-on.ru [88.198.49.164]) by mail.u-on.ru (Postfix) with ESMTPA id D20DBD00081 for <[email protected]>; Sun, 14 Sep 2014 19:02:00 +0400 (SAMT)
X-Received: by 10.112.129.228 with SMTP id nz4mr21113038lbb.9.1410706592950; Sun, 14 Sep 2014 07:56:32 -0700 (PDT)
Return-Path: <[email protected]>
Received-Spf: pass (google.com: domain of [email protected] designates 2a01:4f8:131:122b::2 as permitted sender) client-ip=2a01:4f8:131:122b::2;
Authentication-Results: mx.google.com; spf=pass (google.com: domain of [email protected] designates 2a01:4f8:131:122b::2 as permitted sender) [email protected]; dkim=neutral (no key for signature) [email protected]
Dkim-Signature: v=1; a=rsa-sha256; c=simple/simple; d=u-on.ru; s=default.private; t=1410706920; bh=P9joGKJObSki15Bd60lDp1CHDDzQWerfYCXYmdt9oIA=; h=Message-ID:Date:Subject:From:Reply-To:To:MIME-Version: Content-Type:Content-Transfer-Encoding; b=wRuaRrcXKo9QpmD9HMO098WKepJDa2Qu22TLDBPBKRWCLozTntOwvww6MjmZivFHt A7ceLZ32uaB6rfjJyes3HujgSZ4HK4fbD8B/3mvr2kryg8UyPsJFjDd/LX92VL/W6Q tPBd81QnuTpb+siI9Pg40K6N9GIFA+sCE5pWd5cU=
Message-Id: <[email protected]>
Mime-Version: 1.0
Content-Type: text/html; charset=windows-1251
Content-Transfer-Encoding: quoted-printable

Can't fix "dkim=neutral (no key for signature) [email protected]" in Authentication-Results, what could be the problem?

Answer 1

In the signature
s=default.private;Then the public key should be placed in default.private._domainkey.u-on.ru
But I think it's better to change the selector in the mailer config to default or mail instead of default.private. It's a bit more aesthetic :)

Answer 2

Where do you store the dkim public key?

dig mail._domainkey.u-on.ru TXT

; <<>> DiG 9.3.5-P1 <<>> mail._domainkey.u-on.ru TXT
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11322
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;mail._domainkey.u-on.ru.       IN      TXT

;; AUTHORITY SECTION:
u-on.ru.                10800   IN      SOA     ns1.first-ns.de. postmaster.robot.first-ns.de. 2014091420 14400 1800 604800 86400

;; Query time: 78 msec
;; SERVER: 192.168.2.148#53(192.168.2.148)
;; WHEN: Sun Sep 14 19:21:16 2014
;; MSG SIZE  rcvd: 109