For several months I have been receiving a "Email System Error - Returned Email with Subject: xxxxx" message when sending an email to one specific btinternet account from my own btinternet account. However, the error detail then relates to a mail.co.uk account with the same user name as the btinternet.com account to which the eamil was addressed.
I don't get this message for any other of my contacts with btinternet accounts.
The actual email is being delivered successfully to the recipient who is blithely unaware of the bounce message.
Why am I receiving this from mail.co.uk and how do I fix the problem?
This is the detail of the email I receive each time - the contacts actual details in both email addresses have been replaced with "contactname" to preserve anonymity.
Each of the following recipients was rejected by a remote mail server. The reasons given by the server are included to help you determine why each recipient was rejected.
Reason: Recipient does not exist
Reporting-MTA: dns; re-prd-fep-041.btmx-prd.synchronoss.net
Arrival-Date: Tue, 15 Jun 2021 11:18:26 +0100
Received-From-MTA: dns; re-prd-rgout-004.btmx-prd.synchronoss.net (10.2.54.7)
Final-Recipient: RFC822; <email@example.com>
Remote-MTA: dns; mx02.mail.de (220.127.116.11)
Diagnostic-Code: smtp; 550 Recipient does not exist
X-Actual-Recipient: RFC822; <firstname.lastname@example.org>