DKIM header in mail from Plesk server contains lenght tag: Body Hash Did Not Verify

Symptoms

• In analyzing headers of email sent from the Plesk server, mxtoolbox.com Email Header Analizer shows the following error:

  CONFIG_TEXT: Body Hash Did Not Verify

  

• DKIM policy is configured in the Plesk.

• Lenght tag can be found in the email header (l=663):

  CONFIG_TEXT: v=1; a=rsa-sha256; c=relaxed/relaxed; d=wna.jp; s=default; t=1548437364; bh=XPOALMihvVieKHybTr2G8RH3tg93XgGJyTxTAoZreoI=; l=663; h=From:Subject:To; b=FlHzW/BaAAZibibuhoEvU45+nhJZncg59Jc/7dLsMhNr4alRyVYuPrnr6gNv3+b

Cause

This is a Plesk bug with ID PPPM-9978, which is planned to be fixed in future product updates.

Resolution

As a temporary workaround apply the solution below:

1. Connect to the server via SSH.

2. Create a backup of the initial configuration file:

   # cp -a /usr/local/psa/handlers/hooks/dk_sign{,.bak}

3. Download the file attached, extract the archive.

   # wget https://support.plesk.com/hc/en-us/article_attachments/360023796254/dk_sign.zip

   # unzip dk_sign.zip

4. Set correct permissions and ownership to the file:

   # chmod 750 dk_sign

   # chown root:popuser dk_sign

5. Replace the original file:

   # mv dk_sign /usr/local/psa/handlers/hooks/dk_sign