Other mail system problem 552

[#1]

I was awaiting an important reply from an Amazon Seller with whom I had a problem and see (via my Amazon buyer account) that their attempt to contact me failed with the following message (this is an extract 😞
The following message to <my email address@plus.com> was undeliverable.
The reason for the problem:
5.3.0 - Other mail system problem 552-'Spam Message Rejected '
--7Bv3w.4rXOS9Qfr.1clZBV.FtYL5cV
content-type: message/delivery-status
Reporting-MTA: dns; smtp-out-127-10.amazon.com
etc etc...
Anyone know why this specific sender would have been zapped, and what I can do about it?  I wanted to raise this problem with Plusnet support but the e-mail contact link I have used previously has disappeared...
Thanks for reading

[#2]

It would seem that the incoming message has been rejected because its source and/or contents match a Cloudmark spam fingerprint.
You can contact Plusnet Support to query this by going to Contact Us linked at the top of the Plusnet website and clicking the Need to ask us a question? link.

[#3]

Thanks very much for replying .I don't know what it is you have referrred to but I have now managed to raise a questiion and have added your comment to that.

[#4]

That's fine, hope they can resolve this problem for you.