For the record, in practice it is TOO limiting to expect both forward
and reverse match, and especially if your system doesn't look at
multiple records correctly, eg ANY A <> ANY PTR should be enough.
But expect a lot of false positives if trying to get them to match in
any case. As long as the PTR record is sane, the A record is sane,
domain in the PTR is sane, be happy with that ;)
PS, on another note.. don't SendGrid and Adobe and other big senders
check their IP(s) on RBL listing services (HetrixTools, MXToolbox etc)
Had it just recently pointed out that a major airline had their sending
IP on an RBL since 2019, and they never noticed or removed themselves?
On 2022-01-20 11:17 a.m., Faisal Misle via mailop wrote:
That looks like Sendgrid, so they may be able to ping United.
I have the contact of their CTO, but you may get quicker help from
SendGrid.
On 1/20/22 2:04 PM, Glowfish Domainadministrator via mailop wrote:
Hi,
Emails from united are getting rejected by our postfix mailserver. The
mails seem to be from United Airlines (Mileage Plus).
Jan 20 19:16:45 mta01 postfix/postscreen[126746]: CONNECT from
[50.31.61.242]:47664 to [xxx.xxx.xxx.xxx]:25
Jan 20 19:16:45 mta01 postfix/postscreen[126746]: WHITELISTED
[50.31.61.242]:47664
Jan 20 19:16:45 mta01 postfix/smtpd[126747]: warning: hostname
o1.email.smallbusiness.mileageplus.com does not resolve to address
50.31.61.242: Name or service not known
Jan 20 19:16:45 mta01 postfix/smtpd[126747]: connect from
unknown[50.31.61.242]
Jan 20 19:16:46 mta01 postfix/smtpd[126747]: Anonymous TLS connection
established from unknown[50.31.61.242]: TLSv1.2 with cipher
ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)
Jan 20 19:16:47 mta01 policyd-spf[126752]: prepend Received-SPF: Pass
(mailfrom) identity=mailfrom; client-ip=50.31.61.242;
helo=o1.email.smallbusiness.mileageplus.com;
envelope-from=bounces+6242581-cfae-recei...@domain.tld@em7341.united.com;
receiver=<UNKNOWN>
Jan 20 19:16:47 mta01 postfix/smtpd[126747]: NOQUEUE: reject: RCPT
from unknown[50.31.61.242]: 450 4.7.1
<o1.email.smallbusiness.mileageplus.com>: Helo command rejected: Host
not found;
from=<bounces+6242581-cfae-recei...@domain.tld@em7341.united.com>
to=<recei...@domain.tld> proto=ESMTP
helo=<o1.email.smallbusiness.mileageplus.com>
Jan 20 19:16:47 mta01 postfix/smtpd[126747]: disconnect from
unknown[50.31.61.242] ehlo=2 starttls=1 mail=1 rcpt=0/1 quit=1
commands=5/6
Anyone here from united ? Or anyone has an idea what I can do to make
them pass without opening my mailserver to all other wrongly
configured domains ?
KR
Daniel
_______________________________________________
mailop mailing list
mailop@mailop.org
https://list.mailop.org/listinfo/mailop
_______________________________________________
mailop mailing list
mailop@mailop.org
https://list.mailop.org/listinfo/mailop
--
"Catch the Magic of Linux..."
------------------------------------------------------------------------
Michael Peddemors, President/CEO LinuxMagic Inc.
Visit us at http://www.linuxmagic.com @linuxmagic
A Wizard IT Company - For More Info http://www.wizard.ca
"LinuxMagic" a Registered TradeMark of Wizard Tower TechnoServices Ltd.
------------------------------------------------------------------------
604-682-0300 Beautiful British Columbia, Canada
This email and any electronic data contained are confidential and intended
solely for the use of the individual or entity to which they are addressed.
Please note that any views or opinions presented in this email are solely
those of the author and are not intended to represent those of the company.
_______________________________________________
mailop mailing list
mailop@mailop.org
https://list.mailop.org/listinfo/mailop
