I do not know what is going on here: This is found in the maillog on inet17
Nov 7 16:40:21 inet17 postfix/smtpd[79991]: NOQUEUE: reject: RCPT from unknown[216.185.71.31]: 450 4.1.2 <r...@samba-01.brockley-2016.harte-lyne.ca>: Recipient address rejected: Domain not found; from=<> to=<r...@samba-01.brockley-2016.harte-lyne.ca> proto=ESMTP helo=<mx31.harte-lyne.ca> But this is what I get when I run dig on the same host a moment later: [root@inet17 /var/spool/imap]# dig SAMBA-01.BROCKLEY-2016.HARTE-LYNE.CA ; <<>> DiG 9.12.1-P2 <<>> SAMBA-01.BROCKLEY-2016.HARTE-LYNE.CA ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 706 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;SAMBA-01.BROCKLEY-2016.HARTE-LYNE.CA. IN A ;; ANSWER SECTION: SAMBA-01.BROCKLEY-2016.HARTE-LYNE.CA. 60 IN A 192.168.8.65 ;; AUTHORITY SECTION: BROCKLEY-2016.HARTE-LYNE.CA. 172800 IN NS samba-02.BROCKLEY-2016.HARTE-LYNE.CA. BROCKLEY-2016.HARTE-LYNE.CA. 172800 IN NS samba-03.BROCKLEY-2016.HARTE-LYNE.CA. BROCKLEY-2016.HARTE-LYNE.CA. 172800 IN NS samba-04.BROCKLEY-2016.HARTE-LYNE.CA. BROCKLEY-2016.HARTE-LYNE.CA. 172800 IN NS samba-05.BROCKLEY-2016.HARTE-LYNE.CA. BROCKLEY-2016.HARTE-LYNE.CA. 172800 IN NS SAMBA-01.BROCKLEY-2016.HARTE-LYNE.CA. ;; Query time: 1 msec ;; SERVER: 216.185.71.33#53(216.185.71.33) ;; WHEN: Wed Nov 07 16:41:16 EST 2018 ;; MSG SIZE rcvd: 187 Why does dig find the domain while Postfix does not? I am guessing that I have a misconfiguration somewhere but I cannot think of where. -- *** e-Mail is NOT a SECURE channel *** Do NOT transmit sensitive data via e-Mail Do NOT open attachments nor follow links sent by e-Mail James B. Byrne mailto:byrn...@harte-lyne.ca Harte & Lyne Limited http://www.harte-lyne.ca 9 Brockley Drive vox: +1 905 561 1241 Hamilton, Ontario fax: +1 905 561 0757 Canada L8E 3C3