I have been having a problem with e-mail that I send being rejected. Today I had 5 e-mails which were undeliverable. I tried my son on both his work e-mail and gmail, and both were rejected, with the following messages:
e-mail 1:
This is the mail system at host mx-out.tt.xion.oxcs.net.
I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can delete your own text from the attached returned message.
The mail system
<r.***@G****man.com>: host
g****man-com.mail.protection.outlook.com[52.101.68.0] said: 550 5.7.1
Service unavailable, Client host [153.92.124.143] blocked using Spamhaus.
To request removal from this list see
https://www.spamhaus.org/query/ip/153.92.124.143 AS(1440)
[DU6PEPF00009528.eurprd02.prod.outlook.com 2025-07-14T09:01:04.063Z
08DDBE8F9DDF6760] (in reply to RCPT TO command)
e-mail 2: Your message did not reach some or all of the intended recipients.
Subject: FW: Undelivered Mail Returned to Sender
Sent: 14/07/2025 10:27
The following recipient(s) cannot be reached:
Rupert (w*****d@gmail.com) on 14/07/2025 10:27
550 5.7.1 Reject for policy reason
My son says this must be to do with the security credentials of the talktalk mailserver, as this effected both his work domain and gmail.
Please advise why this is happening, and how to stop this in future.
