Mail marked as spam


I am trying to forward an email that I got, but keep getting “the email could not be sent”, and NDR email from Mailer-Deamon.
“I am deeply sorry, but I was not able to deliver your mail to the following addresses:”

If I send a normal email, it goies through.
If I save the email I want to forward, as a PDF and attach it, it gets marked as spam…

Tried sending to both the person I intended, and to my address, both got blocked.

In the end, I had to send the PDF saved email from address.

I tried looking through my logs for an explenation, but I cant see why it thought it was spam.

I experienced this again yesterday.

Anyone got any ideas?


Without having any hints from your logs (like PROCESSING and SMTP-OUT preferable both on Protocol Communication) we have no means to provide a possbile explanation for your particular issue.


Queue Processing.txt (155.9 KB)
SMTP Sending.txt (39.7 KB)

Here are the 2 log files, edited to remove personal information.

I received an email from , tried to reply to it but got an error immediately.
Tried forwarding their reply to my address, but it was blocked with the same error.
Tried sending a fresh email to my address, and I was able to send that email.

Do you see any reason for this, in these logs?

It is possible the mail server is on the inside of my ISP, parallel to the relay server and somehow got misinterpreted by them, as my ISP and Fagne are related companies, but that would not prevent me from forwarding the email?

Hello Peter,

So your message was rejected by the remote server = (which is not the MX of the recipient domain) with the following explanation:

SMTP-OUT:00000003: << 550 5.7.1 Rejected. This message has been marked as spam. client=<My_External_IP> job_id=5AF4D80026
SMTP-OUT:00000003: Error sending data for mail 3B366E; server response code: 550 (5.7.1 Rejected. This message has been marked as spam. client=<My_External_IP> job_id=5AF4D80026)

You may find the reason only if you will ask them (the operator of the SMTP relay service) providing above info and the message-id of that message, like: as extracted from:

PROCESSING:003B366E: New mail <> ...



Have sent them an email :slight_smile: