Hi all! I recently set up an relay SMTP server on a host of Digital Ocean, using Debian and Postfix. The main reason for setting up this relay is that the cPanel VPS is hosted at Godaddy, and they force everyone to send email through their shared SMTP relay. As expected, that shared relay is continually being flagged for spam. So the outgoing emails are routed through this server. Usually everything worked smoothly. Mails to accounts on Google, Yahoo, Hotmail and other servers are delivered. But I found a problem with a specific domain: ----------------------------------------------------------------------- Sep 7 14:36:11 smtp postfix/smtp[8036]: 5EAA520AAD: to=<xxxx@lkeusa.com>, relay=lkeusa.com[50.87.144.56]:25], delay=13, delays=0.91/0.06/6.1/5.9, dsn=5.0.0, status=bounced (host lkeusa.com[50.87.144.56] said: 550-Please turn on SMTP Authentication in your mail client, or login to the 550-IMAP/POP3 server before sending your message. smtp.server.com 550-[x.y.z.t]:41988 is not permitted to relay through this server 550 without authentication. (in reply to RCPT TO command)) ----------------------------------------------------------------------- I'm not sure why this specific domain is complaining in this way. Another thing that is strange to me is that apparently a dig query is not returning nothing: ----------------------------------------------------------------------- $ dig -t mx lkeusa.com ; <<>> DiG 9.9.5-9+deb8u6-Debian <<>> -t mx lkeusa.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 31796 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;lkeusa.com. IN MX ;; Query time: 531 msec ;; SERVER: 10.1.0.6#53(10.1.0.6) ;; WHEN: Thu Sep 08 13:48:38 ART 2016 ;; MSG SIZE rcvd: 39 ----------------------------------------------------------------------- But Postfix was trying to deliver the mail in 50.87.144.56. Maybe they were making changes to the remote server? Thanks in advance. Kind regards, Daniel
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