Undelivered Mail Returned to Sender （2024.03.16）
This is the mail system at host mx3.hk-net.de.
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
Recipient address rejected: User unknown in virtual mailbox table (in reply
to RCPT TO command)
