We have many customers who use your Newsletter filtering, one of their biggest complaints is that they can only whitelist using the envelope sender.
This causes an issue because newsletters are normally sent through marketing companies such as sendgrid.net or cmail.com and are made up of randomstring@cmail.com
The random string normally changes between newsletter runs, as it's used to trace bouncebacks, and this makes it impossible to whitelist the sender.
Equally whitelisting the domain means that you will allow that newsletter, but also the newsletters of any other company who use that marketing sender.
If they were able to whitelist the body from address, which relates to the company sending it, rather than the newsletter provider then there would be no issue.
For example:
Env From: {fjef=2494ff=mermaid-marine=co=uk@cmail2.com}
Bdy From: {noreply@mermaid-marine.co.uk
whitelisting cmail2.com would allow any newsletters from any company who relays trhough cmail2.com not just the mermaid marine newsltter, whereas if whitelisting the bodyfrom this would prevent the issue.