How do I stop Plus.net from rejecting emails as spam when they are not?

[#1]

I sent an email to two different plus.net addresses and they were both rejected and not delivered because they had the URL http://www.suffolkphotography.org/  in them.  This is not a spam or malware site, so why was the email rejected rather than delivered?  How do I get round this problem and prevent it happening?  I need to communicate the URL, that is the purpose of the email.

[#2]

It's the incoming email server that applies the spam filter so no reason to believe that anyone who does not have a Plusnet email address will have problems.

[#3]

The relevant bit is:-

X-Gm-Message-State: ALyK8tK8xWw6NbtVUrnPE9iyI8Wukj+EasEFdlTQj6zc5r/m5oVSo/AEwahZqyk9pMBHOwnwowzZJd+H/qjevQ==
X-Received: by 10.107.35.129 with SMTP id j123mr3879058ioj.4.1467120251449;
 Tue, 28 Jun 2016 06:24:11 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.107.128.155 with HTTP; Tue, 28 Jun 2016 06:24:11 -0700 (PDT)
From: Jeremy Boden <xxxxxx@gmail.com>
Date: Tue, 28 Jun 2016 14:24:11 +0100
Message-ID: <CAHVHDdRy9_+0N+Tiw=zyf+N70iTR1g+B57oqOmfpe4BYXoTwzg@mail.gmail.com>
To: jeremyboden@xxxxxx.plus.com
Content-Type: multipart/alternative; boundary=001a1140fbd06e3e890536568d9a
X-pn-pstn: Spam 1
X-PN-Spam-Filtered: by PlusNet MXCore (v5.00)
Subject: [-SPAM-] test

So its yet another Plusnet fail...

[#4]

@bobpullen I just checked and including that url in a post does trigger the spam or virus checker which is rather silly

This is the bounce message

552 CDWZ1t0092ZcWc101DWabH message rejected due to spam or virus. If you believe this is in error please login to your portal or contact your ISP support team.

Even sending it as plain text didn't help

[#5]

@jgw321 wrote:

I sent an email to two different plus.net addresses and they were both rejected and not delivered because they had the URL http://www.suffolkphotography.org/  in them.  This is not a spam or malware site, so why was the email rejected rather than delivered?

The spam detection relies on real-time threat reporting, and the domain was featured in emails that have been reported as spam. Similar emails are likely to have been sent to 'honeypot' addresses as well.

I've had the reputation of the domain cleared so the problem should be resolved. It's likely to happen again if similar activity is reported though.

@ReedRichards wrote:

It's the incoming email server that applies the spam filter...

We filter outbound mail as well.

@VileReynard wrote:

The relevant bit is:-

X-pn-pstn: Spam 1
X-PN-Spam-Filtered: by PlusNet MXCore (v5.00)
Subject: [-SPAM-] test

So its yet another Plusnet fail...

I'm not sure those headers are even there any more. Have you seen them recently? The more current ones look like this:

X-CM-Score: 0.00
X-CNFS-Analysis: v=2.2 cv=Y8O6iVWN c=1 sm=1 tr=0
 a=u3acNTG+s+B6jBoILOsovw==:117 a=ppQbopU1dbM4pibJhI9yag==:17
 a=pD_ry4oyNxEA:10 a=JqEG_dyiAAAA:8 a=8wzNPhNUAwzlDExG8-AA:9
 a=oUT-n_LpDmc8rvajOR8A:9 a=Kpz5TQiPmnc2wa39:21 a=UiCQ7L4-1S4A:10
 a=_W_S_7VecoQA:10 a=U04FSIGNRx3ScUM3zguK:22

Regardless, you're talking about incoming email, whereas the OP's question is about outbound mail.