See a double-bounce mail generated by my postfix

I would like to be able to see an example of a double-bounce message
generated by my postfix (3.3.0) server. Can I get my postfix to send me
(say to an unrelated external mailbox) a double-bounce message?
Alternatively is there a way I can save, on the server, the double-bounce
message as and when it sends it to a third party? (These messages are not
saved locally by setting always_bcc.)

A concern I have is that qmgr records the double bounce message as coming
from <> - which seems odd:

2018-08-08 08:04:41 vps344444 postfix/bounce[28259]: 059F147CEF: sender
non-delivery notification: 0C89547CF1
2018-08-08 08:04:41 vps344444 postfix/qmgr[20724]: 059F147CEF: removed
2018-08-08 08:04:41 vps344444 postfix/qmgr[20724]: 0C89547CF1: from=<>,
size=4973, nrcpt=1 (queue active)


Re: See a double-bounce mail generated by my postfix

By Dominic Raferd at 08/08/2018 - 03:03

Sorry I have now found an example of a bounce message so the original part
of my question is no longer relevant.

The bounce message sender is indeed '<>', and the From header is
'MAILER-DAEMON@[mydomain]'. My problem with this is that although the
message is DKIM-signed (by opendkim), it fails DMARC alignment because of
the mismatch between sender and 'From:' header. The only related
non-default settings I have are:
canonical_maps = hash:/etc/postfix/canonical inline:{$double_bounce_sender@

<> root
www-data root
postfix root
root@localhost root

Maybe the inline table rewriting is not working? I would expect both the
sender and the 'From:' header to be double_bounce@[mydomain]