Strange bounce message returned for incoming email

[#1]

Hi,
I wonder if anyone here can suggest any reasons for the bounce message copied below. The email in question was sent to me a couple of times and kept bouncing back to the sender and not arriving.  I can't quite follow whether it is complaining too big (yet it was only ~140kb and other large test emails work fine) or if it has declared it spam but then why bounce? If spam can I find the scoring anywhere?
Thanks for any suggestions so I can make sure I at least understand when it might happen again.
Cheers
Alistair
-----Original Message----- From: Mail Delivery Service
Sent: Thursday, August 14, 2014 6:00 PM
To: d#######@btinternet.com
Subject: Delivery Status Notification
- These recipients of your message have been processed by the mail server:
circuitfinance@s##########ls.plus.com; Failed; 5.3.4 (message too big for system)
  Remote MTA mx.avasin.plus.net: network error

- SMTP protocol diagnostic: 552 Spam Message Rejected
Fw_ Your Steeles Removals Ltd invoice 336091 is attached in PDF format.eml

[#2]

Magic this forum, I think I've found the answer.
I suspect that the domain that the original email came from, steelesremovals.co.uk is blacklisted on the Cloudmark list used by the Plusnet servers.  What was confusing was that I didn't receive the email from them directly I was getting (or rather not getting) forwarded copies. When I finally obtained a copy via another email address and tried to reply via the Plusnet SMTP server the mere presence of that domain as text in an email body stops the email sending. I presume this is therefore the reason why the emails weren't being received.
Hopefully this might help if this thread comes up in a search!
Cheers,
Alistair

[#3]

Quote from: sandwithbells

I suspect that the domain that the original email came from, steelesremovals.co.uk is blacklisted on the Cloudmark list used by the Plusnet servers.

You're right, it is.

Quote from: sandwithbells

What was confusing was that I didn't receive the email from them directly I was getting (or rather not getting) forwarded copies.

That's not unusual. It's Cloudmark's Authority content filters that are triggering the rejection. They look at the content of emails as well as their origin.
I'll see if I can get the reputation of the domain reset for you...

[#4]

Quote from: Bob

I'll see if I can get the reputation of the domain reset for you...

Done, so all should be well now.

[#5]

Quote from: Bob

Done, so all should be well now.

Thanks Bob, should save any future confusion hopefully.
Cheers,
Alistair