Hello,
I have a question regarding DKIM signing on Postfix bounce back messages.
I was tuning my Dovecot installation around quotas. I sent a test message from
Hotmail to a test account on my server to test generation of a bounce back when
a user exceeds their quota. The message was successfully generated and then
relayed via Postfix back to the Hotmail account, but I noticed the bounce back
message went into the Hotmail junk folder.
Inspecting the message I saw that I was not DKIM signing messages generated by
Postfix or via sendmail. I changed my Postfix config to include:
/etc/postfix/main.cf
internal_mail_filter_classes = bounce
non_smtpd_milters = unix:/var/run/opendkim/opendkim.sock
Generating a new test message confirmed that bounce back messages are now DKIM
signed . . . BUT I noticed this line in: man 5 postconf
internal_mail_filter_classes
NOTE: It's generally not safe to enable content inspection of
Postfix-generated email messages.
My question is - will enabling DKIM on bounce back messages cause me problems
or is that warning more for content filters that attempt to mangle/modify the
bounce back messages ?
Thanks,
- J
