Hi,
That error is not coming from the Broadcom servers, but from the recipient's server (h002.tcu.gov.uk, as shown in the message). A bit of googling suggests that the server is IBM Domino / Lotus Notes. The message suggests that the message causing the problem has further messages attached, possibly, which in turn have other messages attached - but that is just a guess. I suggest you get in touch with the admin of the recipient server if you can; or try sending the messages without attachments.
Paul
Original Message:
Sent: Sep 16, 2022 03:43 PM
From: Sergio Junior
Subject: Remote Server Returned 554 5.0.0
Hi folks.
Some emails are showing the message shown in the attached image.
Could anyone help me understand why?
Thanks.