[Discuss] Mail list mis-configured(?) no DKIM and no rDNS and no SPF

[ron at bclug.ca (Ron)]

I might be mistaken, but it looks like there's mis-configured email 
server settings.

While reviewing and tightening up security settings on one of my email 
servers, I found some log entries indicating problems...


DKIM on the list's messages (signed messages but no key in DNS?):

https://mxtoolbox.com/SuperTool.aspx?action=dkim%3adefault._domainkey.driftwood.blu.org&run=toolpage


Feb  4 23:31:49 kwvoip postfix/cleanup[1388571]: 75EAD8106B: reject: 
header Authentication-Results: driftwood.blu.org;??dkim=fail 
reason="signature verification failed" (2048-bit key) 
header.d=millermicro.com header.i=@millermicro.com header.b="rOHhWpz1" 
from unknown[131.226.247.88]; 
from=<natickfoss-discuss-bounces+ron=bclug.ca at lists.blu.org> 
to=<ron at bclug.ca> proto=ESMTP helo=<driftwood.blu.org>: 5.7.1 "DKIM 
FAIL: invalid DKIM: your server's DKIM record is missing or invalid"

$ dig +short txt default._domainkey.driftwood.blu.org
$



Also, not sure if BLU or Natick, but rDNS does not seem setup for email 
server:

Feb  4 23:31:48 kwvoip postfix/smtpd[1388566]: NOQUEUE: reject_warning: 
CONNECT from unknown[131.226.247.88]: 450 4.7.25 Client host rejected: 
cannot find your hostname, [131.226.247.88]; proto=SMTP

$ dig  +short -x $(dig +short driftwood.blu.org)
$




And, no SPF too?!?

https://mxtoolbox.com/SuperTool.aspx?action=spf%3adriftwood.blu.org&run=toolpage#

Feb  4 23:31:49 kwvoip policyd-spf[1388569]: prepend Received-SPF: None 
(mailfrom) identity=mailfrom; client-ip=131.226.247.88; 
helo=driftwood.blu.org; 
envelope-from=natickfoss-discuss-bounces+ron=bclug.ca at lists.blu.org; 
receiver=<UNKNOWN>

$ dig +short txt driftwood.blu.org
$