Question

DKIM TXT DNS record mail._domainkey exists but verifier.port25.com says it doesn't

I followed the excellent article: https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-dkim-with-postfix-on-debian-wheezy to set up DKIM on my server. I created the two TXT records exactly as required. My domain is called realassurance.com. However the authentication check using a test email to: check-auth@verifier.port25.com returns the following in the DKIM section stating that mail._domainkey.realassurance.com doesn’t exist (see below), when it does. Having read as many blog articles as I could find about this I have ensured the text is in quotes and I am sure it is not a propagation issue as I used mxtoolbox.com (and other similar online tools) to check for mail._domainkey.realassurance.com which was found as a TXT record ok.

Also I note in the report below, it reports the DNS record as TXT (NXDOMAIN) - whatever that means.

No idea what to do next. Can someone please help?

Dave


DKIM check details:

Result: permerror (key “mail._domainkey.realassurance.com” doesn’t exist) ID(s) verified: Canonicalized Headers: to:check-auth@verifier.port25.com’0D’‘0A’ from:John’20’jdt2@realassurance.com’0D’‘0A’ subject:test’0D’‘0A’ date:Sun,‘20’23’20’Apr’20’2017’20’15:53:34’20’+0800’0D’‘0A’ dkim-signature:v=1;'20’a=rsa-sha256;'20’c=relaxed/simple;'20’d=realassurance.com;'20’s=mail;'20’t=1492934013;'20’bh=frcCV1k9oG9oKj3dpUqdJg1PxRT2RSN/XKdLCPjaYaY=;'20’h=To:From:Subject:Date:From;'20’b=

Canonicalized Body: ‘0D’‘0A’

DNS record(s): mail._domainkey.realassurance.com. TXT (NXDOMAIN)

NOTE: DKIM checking has been performed based on the latest DKIM specs (RFC 4871 or draft-ietf-dkim-base-10) and verification may fail for older versions. If you are using Port25’s PowerMTA, you need to use version 3.2r11 or later to get a compatible version of DKIM.

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Hello there,

You can use a DKIM checker tool like the one provided from mxtoolbox and check whether the generated key is valid.

https://mxtoolbox.com/dkim.aspx

I’ll also highly recommend not to send emails via port 25 as this is insecure and a lot of email providers will discard any emails coming from it. You can also use an email provider like Sendgrid to send your emails.

Hope that this helps! Regards, Alex

@dave102

When using MXToolbox, I was able to verify the DKIM entry easily. I’m seeing the following:

v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDfWHolALh8Kohz+hSyWWRArUQJbo+lDAKKIUIQ39s3V/AQOO4IcihyF7s8ZFl936NcF6wcpEHXzvnYt5g19+s0VtY8Hc+CM8+a3AC4nz1QuGeitzNDp8f/mNkjZA33k3cnMFj5286Aej/YYsMzMsUQbRzXgYk9MKphJEBAIpYc2wIDAQAB

It is possible that at the time of checking, the DNS entry hadn’t fully propagated, thus when they did a check, it failed. On my end, as of this reply, it’s showing up and appears valid.