Yeah.. always take stats with a grain of salt..
Besides, we know that spammers adopt these things faster than real
companies.. hehehe..
But the ones that don't have it (fcRdns) are often the emails that
people scream the most about missing.
oaky, going back to looking at the threat research stuff.. I have been
amiss with sending my state of the union reports the last couple of weeks.
On 2023-05-09 12:18, Tobias Fiebig via mailop wrote:
Heho,
hm, not sure. Looking at the 'email-security-scans.org' data, fcrdns is
at ~95.5% of senders. For comparison:
DKIM: ~55.2%
SPF & Valid: ~91.0%
TLS: ~96.0%
Greylisting (attempting to resend): ~97.4%
IPv4: ~97.9%
IPv6 (sending): 56.2%
IPv6 (sending+auth DNS+rec DNS): ~35.7%
So even though that sample is a bit biased, i'd say that fcrDNS is more
'lived practice' than SPF. ;-)
With best regards,
Tobias
On Tue, 2023-05-09 at 11:40 -0700, Michael Peddemors via mailop wrote:
Hi Laura,
I think we have to disagree here. The PTR naming is set via
SendGrid.
It doesn't NEED to be the same as the A record. This is for those
MTA's
that do forward/reverse matching, which isn't always successful.
Yes, doing that for a IPv6 email address to satisfy Google, go ahead.
But nothing wrong with sending an email from a PTR with a name, that
doens't have the FQDN forward/reverse matched.
As long as there is a URL associated with the domain name.
eg. http://mileageplus.com (Redirect to UA site URL)
Perfect forward/reverse FQDN matching is still a little aggressive
IMHO,
and especially problematic. Some people think they need 20 PTR
records,
one for each A record.. (No, that is worse)
Postfix does allow forward/reverse checking, I would NOT enable that
for
the IPv4 space (yet)
On 2023-05-09 10:22, Laura Atkins via mailop wrote:
That’s a Sendgrid IP, they likely told UA to put in a DNS record,
but UA
never did. ¯\_(ツ)_/¯ n
On 9 May 2023, at 18:01, Stephen Frost via mailop
<mailop@mailop.org>
wrote:
Greetings,
I'm getting some inbound email attempts that I believe are
legitimate
from United Airlines that are being rejected due to:
May 9 12:55:38 tamriel postfix/smtpd[1221960]: warning: hostname
o1.email.smallbusiness.mileageplus.com does not resolve to
address
50.31.61.242
Tracking this back, near as I can tell, postfix is correct here
in that
50.31.61.242 / 242.61.31.50.in-addr.arpa resolves to
o1.email.smallbusiness.mileageplus.com but
o1.email.smallbusiness.mileageplus.com doesn't seem to actually
exist:
dig o1.email.smallbusiness.mileageplus.com a
;o1.email.smallbusiness.mileageplus.com.IN A
;; AUTHORITY SECTION:
smallbusiness.mileageplus.com. 600 INSOA
vndcdf-fs0000-gma3-vip.ual.com. ualipconfig.united.com. 40 10800
3600
2592000 600
Hopefully someone on here is from UA or knows how to get in touch
with
someone there who could like into fixing that.
Thanks,
Stephen
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Visit us at http://www.linuxmagic.com @linuxmagic
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