Messages from Contact form being marked as spam with spamassassin

Hi I hope someone can advise.

I have a server which is used to host a few old sites. The problem is when sending from one of these sites, an email from the contact form page.

Spamassassin then on the receiving server marks it as spam and it bounces. I whitelisted it to allow a message through and it gets this in the headers:

0.0 TVD_RCVD_IP Message was received from an IP address 1.1 KAM_COUK Scoring emails higher due to poor registry security. -0.0 SPF_PASS SPF: sender matches SPF record 0.0 DKIM_ADSP_CUSTOM_MED No valid author signature, adsp_override is CUSTOM_MED 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (name_name[at] 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% [score: 0.5000] 0.7 MIME_HTML_ONLY BODY: Message only has text/html MIME parts 0.0 HTML_MESSAGE BODY: HTML included in message 2.6 RDNS_DYNAMIC Delivered to internal network by host with dynamic-looking rDNS 0.9 NML_ADSP_CUSTOM_MED ADSP custom_med hit, and not from a mailing list 2.0 TO_NO_BRKTS_HTML_ONLY To: lacks brackets and HTML only

So it seems to be RDNS_DYNAMIC and TO_NO_BRKTS_HTML_ONLY that seem to be mainly racking up the points. Then the rest just tips it over the edge!

Weirdly I’ve mapped a reverse DNS record and that seems to work when doing an IP lookup, but in the mail headers it doesn’t show the static ip address for the mail server it was sent from, rather my router ip address! I don’t know if that’s normal or not?

Also is there something in Virtualmin to stop the TO_NO_BRKTS_HTML_ONLY problem?

Thanks for any help.