Mail delivery failed: returning message to sender

[murgero]

So I've been getting an increasing amount of email being "returned to sender" however I've never sent them. I also have confirmed the server never sent them either. This is clearly a spoofing issue. Thankfully a lot more email services use dmarc, dkim, and spf checking (as seen in the error below).

My question to y'all is: have you seen an increase in this behavior recently?

Email is usually similar to the below, but with data not redacted. Usually a one word subject line and one word in the email.

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

SMTP error from remote mail server after end of data:
554 5.7.9 Message not accepted for policy reasons.


Action: failed
Final-Recipient: 
Status: 5.0.0
Remote-MTA: 
Diagnostic-Code: smtp; 554 5.7.9 Message not accepted for policy reasons.

Subject: 

From: 

Date: 

To: