I've had a Linux address since 2010 and I just sent it a test message today as I noticed I wasn't getting any emails from that address anymore.. here is the Postfix error I recently received:

The Postfix program

<jasonb@linux.com>: host smtp1.linuxfoundation.org[140.211.169.13] said: 550
5.1.1 <jasonb@linux.com>: Recipient address rejected: User unknown in
virtual alias table (in reply to RCPT TO command)