WelshProgammer

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!