I tried configuring a mailhost today and it fails with:
450 4.7.25 Client host rejected: cannot find your hostname, [184.94.240.100]
Postfix when configured with reject_unknown_client_hostname is rejecting the mail because the sender has invalid DNS records:
Postfix logs:
Apr 6 11:44:26 mail postfix/postscreen[1602]: CONNECT from [184.94.240.100]:32832 to [xxxx]:25
Apr 6 11:44:26 mail postfix/postscreen[1602]: PASS OLD [184.94.240.100]:32832
Apr 6 11:44:27 mail postfix/smtpd[33315]: warning: hostname vmx.spamcop.net does not resolve to address 184.94.240.100
Apr 6 11:44:27 mail postfix/smtpd[33315]: connect from unknown[184.94.240.100]
Apr 6 11:44:28 mail postfix/smtpd[33315]: NOQUEUE: reject: RCPT from unknown[184.94.240.100]: 450 4.7.25 Client host rejected: cannot find your hostname, [184.94.240.100]; from=<service@admin.spamcop.net> to=<xxxx> proto=SMTP helo=<prod-sc-www02.spamcop.net>
Apr 6 11:44:28 mail postfix/smtpd[33315]: lost connection after RCPT from unknown[184.94.240.100]
Apr 6 11:44:28 mail postfix/smtpd[33315]: disconnect from unknown[184.94.240.100] helo=1 mail=1 rcpt=0/1 commands=2/3
Is it possible for the SC admins to correctly setup DNS or hostname so that the name is resolved properly?
Currently I get:
nslookup 184.94.240.100
100.240.94.184.in-addr.arpa name = vmx.spamcop.net.
# dig vmx.spamcop.net mx
;; QUESTION SECTION:
;vmx.spamcop.net. IN MX
;; ANSWER SECTION:
NO ANSWER
;; AUTHORITY SECTION:
spamcop.net. 59 IN SOA ns1-93.akam.net. hostmaster.akamai.com. 2023032702 300 300 300 300
# dig vmx.spamcop.net a
;; QUESTION SECTION:
;vmx.spamcop.net. IN A
;; ANSWER SECTION:
vmx.spamcop.net. 69 IN A 184.94.240.112
Thanks!