==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.3.2
- Deployed with iRedMail Easy or the downloadable installer? Downloadable installer
- Linux/BSD distribution name and version: Ubuntu 20.04
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MariaDB
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I get a Pass when i run amavisd-new testkeys

However when i check the header of emails that are sent out i get a failed message. I've looked all over the net to try and find a fix but no joy so far.

This is the header of one of the email i sent to Gmail (From RoundCube)

Authentication-Results: mx.google.com;
       dkim=neutral (body hash did not verify) header.i=@vithusel.me header.s=dkim header.b=ztlvdFyd;

DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d="EDITED OUT"; h= content-type:organization:message-id:user-agent:subject:to:from :date:mime-version; s=dkim; t=1609851869; x=1612443870; bh=jZ4qZ VtU5fEMyiILBzsfnnCN91UIpG/1lZ7zHt2tlB0=; b=ztlvdFydCAYUJTlPpYv4p KXDLAupbvVKlsewlNvKOaF2ydqIXqm838oRsDYlsbP55/KjH3xJvAPbl+wlEJ0RS DNri5NYBkzT8lWGvUuoBZ3906J9eJwP6pGKjJWTsa/mgbdu/NJe1MG6V+PQYiGDj 8od6VRA/QhebNh96znJFLs=
X-Amavis-Modified: Mail body modified (using disclaimer) -

I am currently sending adding signatures to emails using the disclaimer. Could this be causing DKIM to Fail?