552 Spam Message Rejected to Plusnet (F9) user

[#1]

This is from a script I'm developing on PlanenetHippo hosting. Any clues?

--1721842146-eximdsn-567498288
Content-type: message/rfc822

Return-path: <xxxx@cloud105.planethippo.com>
Received: from xxxx by cloud105.planethippo.com with local (Exim 4.97.1)
	(envelope-from <xxxx@cloud105.planethippo.com>)
	id 1sWfnT-00000006EBq-0eZR
	for PNMtest@[my domain];
	Wed, 24 Jul 2024 18:29:03 +0100
To: PNMtest@[my domain]
Subject: Entry for Paws at Forest on Saturday.
X-PHP-Script: xxxx/EntryFormTransmit.php for xxxx
 X-PHP-Originating-Script: 1133:EntryFormTransmit.php
From: Jim C <pnmtest@[my domain]
 Content-type:text/plain; charset=iso-8859-1
 Content-Transfer-Encoding: 7bit
Message-Id: <E1sWfnT-00000006EBq-0eZR@cloud105.planethippo.com>
Date: Wed, 24 Jul 2024 18:29:03 +0100

Message created 24 Jul 2024.
Entry for Paws at Forest on Saturday.

[#2]

Solved it. It was unhappy about end of line format in the mail message. Goodness knows why that should trigger spam filter.

Jim C

[#3]

Is the planethippo mail server in the SPF record as an authorised server for your domain ? if not then that will increase any spam score

I suspect the Envelope-From being different to the From might also increase spam score.

Maybe the eol formattting just tipped it over the edge ?