Error 552 on email reply, but not send.

[#1]

I've a contact who works for a legitimate company with a problematic domain. I've had to whitelist their domain in my spam setting to be able to receive emails, or even to forward emails in to Plus from them via another account.

I can send new emails to them without problem. However I can't reply to their emails (in either text or html format, even if I delete the body), getting an error from "System Administrator"...
"552 ... 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."

Obviously there's something in their email headers that's upsetting relay.plus.net or its scanning partner. However I can only find spam options on incoming emails, nothing on outgoing.

Has anyone any ideas what I can do?

[#2]

Welcome to the forums. 

To protect the reputation of the Plusnet relays the email system does not allow spam filtering on outgoing messages to be changed in any way. I think "replies" being treated differently from "new messages" could be due to back references to the origin domain in the headers,

Investigating and fixing this will need staff intervention.. @bobpullen @Kelly can you help please?

[#3]

I wonder if it's related to this post by @Kelly?

[#4]

Hi, 

Still having issues?   Have you got a ticket open with our support teams with email headers on or anything?

[#5]

How does someone raise a ticket?
I can do an online chat, or call, but neither seem good for logging information.
Asking as this is getting worse, and I'm getting emails randomly blocked based on keywords, e.g. "Heron". How weird!

[#6]

Contact chat via the "Contact Us" page and ask them to raise a ticket on your account directed to the email team. Tell them it will concern random blocking of outgoing messages due to perceived spam.

Explain that you were asked to do this on the Community forums to supply personal information for analysis by the team. (You will need to do this by adding information to the ticket once it's been created.)

When you've done that post the ticket number in this topic.

Hope this helps to get the problem resolved.

[#7]

Thanks - ticket raised: #169210117