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
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