552 Spam Message Rejected - is there a way to find out why?

[#1]

I am a plus net customer - but also web admin for a club theatre in London. Our website sends out an email newsletter a couple of times a month. Note this only goes to our paying members who are expecting to receive it as part of their membership subscription. It is definitely not spam, because they are paying a subscription to receive information from the club.
The latest newsletter went out early hours of this morning - and have received a lot of bounces from plus net addresses with 552 Spam Message Rejected.
Would be really helpful to find out if this is a one-off because there was something in this particular newsletters content that plus net didn't like (in which case I can try to make sure we don't do it again) or whether our server has been blacklisted for some reason? I have not seen this level of issue with any previous issues of the newsletter.
Typical headers below with personal details redacted.
Thanks in advance for any advice.
Richard

The original message was received at Fri, 20 Nov 2015 06:44:08 GMT
from [89.248.51.5]
  ----- The following addresses had permanent fatal errors -----
<xxx@xxx.plus.com>
    (reason: 552 Spam Message Rejected )
  ----- Transcript of session follows -----
... while talking to mx.avasin.plus.net.:
>>> DATA
<<< 552 Spam Message Rejected
554 5.0.0 Service unavailable
Final-Recipient: RFC822; xxx@xxx.plus.com
Action: failed
Status: 5.2.2
Remote-MTA: DNS; mx.avasin.plus.net
Diagnostic-Code: SMTP; 552 Spam Message Rejected
Last-Attempt-Date: Fri, 20 Nov 2015 06:44:28 GMT

---------- Forwarded message ----------
From: "iQ (Members' Website)" <postmaster@members.xxx.org.uk>
To: xxx <xxx@xxx.plus.com>
Cc:
Date: 20 Nov 2015 06:44:32 +0000
Subject: Newsletter - Issue 73

[#2]

hard to say what's causing it without seeing a copy of the original email. It's likely to be the sending domain/addess or a hyperlink within the email body that's triggering the spam filter.

[#3]

Surely the Spam filter should only work on incoming mail?

[#4]

No,  all outgoing mail goes through spam filtering.  This helps to prevent the Plusnet relays from being blacklisted.
We do not have the option to turn this off.

[#5]

Sounds like censorship to me, I am disappointed to hear this. I've never sent spam of any sort but to think that my emails are being filtered without any specific reason and without knowing exactly what is being stopped makes me rather annoyed. My grandfather fought in a war so that we had freedom of speech. This is a disgraceful infringement of liberty.

[#6]

It's nothing to do with censorship.
It's a prevention measure to stop abuse of our outbound email estate that ends up in our servers being blacklisted. When this happens, it has the potential to affect every one of our customers from sending email through our SMTP servers and it takes time, money and effort to resolve.
It may also help to know that email sent via the Madasafish SMTP platform passes through exactly the same servers

[#7]

just posted under the other error 552 thread as well...
I too send out regular emails to a number of interest club members, and have happily been doing so on plusnet since 2007
I generally include map links, and web links to club website, facebook etc.
Bob are you saying that it is these links that get 'blacklisted'?
or is it the number of emails with the same content? - this hasn't been a problem 'til now

[#8]

Quote from: stevecarter2

Bob are you saying that it is these links that get 'blacklisted'?

It's typically an email address or URL in the body or headers of the email.

[#9]

Quote from: Bob

It's a prevention measure to stop abuse of our outbound email estate that ends up in our servers being blacklisted.

Fair enough, but you should ban the abusers, not limit the innocent.
Are you saying that our outgoing emails will be rejected if they contain a URL or email address? I really hope not.

[#10]

Quote from: hottroc

Quote from: Bob It's a prevention measure to stop abuse of our outbound email estate that ends up in our servers being blacklisted. Fair enough, but you should ban the abusers, not limit the innocent.

We do disable compromised accounts, but that's a reactive measure and by that point it's often too late, the damage has been done, and our servers have been blacklisted. It also doesn't account for any malware etc. that might be trying to relay unauthenticated spam over our SMTP servers.

Quote from: hottroc

Are you saying that our outgoing emails will be rejected if they contain a URL or email address? I really hope not.

No. Your mail will be rejected if it contains a URL or domain that is recognised by the global threat reporting engine we use. In other words, domains or URLs that have been associated with a recent bout of spam activity (be it wittingly or unwittingly).

[#11]

We are having the same problem. Through trial and error I have pinned this down to a particular email address in the body of the email that I am sending in Windows Live Mail.
When that email address is present in the body of my email, sending it fails with msg 552. When I remove that email address from the body the email sends o.k. I have just spoken to Plusnet support who said I should whitelist the address - but I am able to send emails to the problem email address, I am just not able to send any emails with that email address in the body of the email. I am not using a Plusnet email address but our emails are presumably going out through a Plusnet server.  Can the email address that is being treated as spam within the email body, be removed from Plusnet,s blacklist? How do I go about requesting this?
Thanks.

[#12]

Whitelisting is not going to help.
Try using Webmail to send the message. It /should/ fail with the same error, after which the message will be stuck in your drafts folder. Move it to you junk folder, highlight the email there and then click the 'not spam' toolbar button. Do that a handful of times then give it an hour or two and see if there's any change. If there isn't, drop me a message containing the suspect email address and I'll see if I can do anything to help.

[#13]

Thanks Bob
I don't have a Plusnet email address so if I do this it won't be on Plusnet webmail - is it still worth doing this with another Webmail? Presumably that isn't going to change anything on Plusnet if I do?

[#14]

Drop me a message in which case and I'll take a look.

[#15]

Thanks Bob I have sent you a message.