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I own a domain name

I have implemented SPF and DKIM to avoid my mails being junked. I have also upgraded to DMARC in monitor mode.

Since I received a few failure reports recently I wanted to investigate more. I have only one server sending outbound emails, running postfix + dkimproxy. I trust that dkimproxy has no major software bugs resulting in bad messages.

I have tested ReturnPath's automated DKIM test and this is the part related to DKIM/DomainKeys

DKIM Results
============
Result =  failed: invalid key for signature: Syntax error in tag: \"v
Domain = domain.org
Selector = sel
DNS Record(s) =
    sel._domainkey.domain.org TXT "v=1; p=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; t=s"
    Public Key Length = 4096

DomainKeys Results
==================
Domain = domain.org
Selector = sel
DNS Record(s) =
    sel._domainkey.domain.org TXT "v=1; p=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; t=s"

The mail displays an anonymised DNS record with genuine public key. It reports an error in tag v. A few hours ago I noticed my v tag was v=DKIM1 instead of v=1 as specified in RFC. I thought it was an error made by me during the initial setup months ago and fixed to v=1, but anyway I received one DMARC success from Google.

Let me explain better: I enforced DMARC a couple of days ago. On 4/16 morning I got a mail from Google telling me that DMARC fully passes, then since 4/17 I get all failures. Then I discovered the v=DKIM1 tag and replaced with v=1 without success

I have not modified my DNS records before that.

So, keeping in topic with the question, why does ReturnPath refuse my DKIM DNS record? Is something wrong in my DKIM implementation at DNS level?

[Add] I have just tried port25.com's tester but at least DKIM passes

----------------------------------------------------------
DomainKeys check details:
----------------------------------------------------------
Result:         permerror (DK_STAT_BADKEY: Unusable key, public if verifying, private if signing.)
ID(s) verified: header.From=###########
DNS record(s):
    sel._domainkey.domain.org. 1800 IN TXT ""v=1; p=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; t=s""

----------------------------------------------------------
DKIM check details:
----------------------------------------------------------
Result:         pass (matches From: #########)
ID(s) verified: header.d=domain.org
Canonicalized Headers:
    message-id:<516FBF8A.9050702@domain.org>'0D''0A'
    date:Thu,'20'18'20'Apr'20'2013'20'11:40:26'20'+0200'0D''0A'
    from:#############'0D''0A'
    mime-version:1.0'0D''0A'
    to:check-auth@verifier.port25.com'0D''0A'
    subject:Test'0D''0A'
    content-type:text/plain;'20'charset=ISO-8859-15;'20'format=flowed'0D''0A'
    content-transfer-encoding:7bit'0D''0A'
    dkim-signature:v=1;'20'a=rsa-sha1;'20'c=relaxed;'20'd=domain.org;'20'h='20'message-id:date:from:mime-version:to:subject:content-type'20':content-transfer-encoding;'20's=dom;'20'bh=uoq1oCgLlTqpdDX/iUbLy7J1Wi'20'c=;'20'b=

Canonicalized Body:
    '0D''0A'


DNS record(s):
    sel._domainkey.domain.org. 1800 IN TXT ""v=1; p=MIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAsMMLhxzXkU+tagc44oMi7eX2BsFb8BsWeT8MRL+hxi4Lsosx7tuPm90iYgilNteyJoXuSP5SUf8B2tDAifdzYQhfhctr0hX9b6ocBCukGq5p0GHpNsCPWyFvxZsCkGqLRmkfb0c36quEAWBeQLe4Z/BwXBBiW1g96WFNb2/GRI1+9OHhligdfuo4PPuU+xiwX4GB0Ik50cJL4xTdBf7lrFwoGYa03ZkXuzKxeGE4cTk50OeIs6eqrzAfbmej4nCex2qGOUt1TWI7ZvCY7u3Gxj+XKaE7VFrQACZof+NP0k2pXPHg9saGJqZrr2i6+RoxGD0w/ibjAWij9enwqlnv2ORsZfe+FmXNOLJAhlYvhHaruubDpte1c7V3ZKDceM45ZawnVmSdLCfBrMbsqipzy8NXN5MxuANYFBkx5EDT+Ieab+zqcnf08m9bgDc4RXMYppDT1/lUy6On+nyfZEnJWiH3BUtgxS8X0uXciXbsooTmPnpkzzvvKXAE/Tv3XqL90q51geqP0EmaZI6lRTpiqoX7zFGlEBiiF7/u8oheszATks8LsNZ/boTFy0OVldbYNhxlIuRmqeXkqD6+kM5ObKtMEv3AdaeBiZmvyJTP8tCsSmPt+e954RLlz2HaDjjNnZNgsj/39U2RzZsFbVqW6uyQh36/y1X4joOiPf366GkCAwEAAQ==; t=s""

Public key used for verification: sel._domainkey.domain.org (4096 bits)
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1 Answer 1

I think I found the problem by chance: my DKIM DNS record contained quotes. It was a bad copy&paste.

Perhaps some providers automatically ignore quotes, while others do not.

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