For years, Yahoo have been sending Calendar reminders to an email address that doesn't exist anymore. Then they send an email to my correct (Yahoo) email address saying -
"Sorry, we were unable to deliver your message to the following address.
sdowd@nor.com.au:
550: No Such User Here"

The sdowd@nor.com.au account does not exist. I can't see that non-existent email address mentioned anywhere in my settings, so I obviously can't delete it.

I have written to Yahoo about this some years ago, but got no response

----- Forwarded message -----
From: MAILER-DAEMON@yahoo.com mailer-daemon@yahoo.com
To: "sdowd4u@yahoo.com.au" sdowd4u@yahoo.com.au
Sent: Sunday, 13 December 2020, 12:40:13 am AEDT
Subject: Failure Notice

Sorry, we were unable to deliver your message to the following address.

sdowd@nor.com.au:
550: No Such User Here"

--- Below this line is a copy of the message.
"Rick Sambrook B'Day" reminder

When