I've been having an issue to send mails, mostly to domains using Outlook.com as mailserver.
Jul 5 15:38:20 vm-dns-mail postfix/smtp: B6A3A20113E: to=<firstname.lastname@example.org>, relay=none, delay=189023, delays=189019/0.05/4/0, dsn=4.4.3, status=deferred (Host or domain name not found. Name service error for name=grassvalley-com.mail.eo.outlook.com type=AAAA: Host not found, try again)
But it has a correct MX record:
vm-dns-mail ~/bin # dig mx grassvalley.com [...] ;; ANSWER SECTION: grassvalley.com. 7362 IN MX 5 grassvalley-com.mail.eo.outlook.com.
And I can telnet to it:
vm-dns-mail ~/bin # telnet grassvalley-com.mail.eo.outlook.com 25 EHLO Trying 22.214.171.124... Connected to grassvalley-com.mail.eo.outlook.com. Escape character is '^]'. 220 CO9EHSMHS019.bigfish.com Microsoft ESMTP MAIL Service ready at Fri, 5 Jul 2013 19:45:12 +0000 250-CO9EHSMHS019.bigfish.com Hello [126.96.36.199] 250-SIZE 157286400 250-PIPELINING 250-ENHANCEDSTATUSCODES 250-STARTTLS 250-AUTH 250-8BITMIME 250-BINARYMIME 250 CHUNKING
I thought it was an IPV6 issue, as this VM is unable to connect to IPV6. So I added this line to main.cf:
inet_protocols = ipv4
But it merely changed the issue to this:
Jul 5 21:41:38 vm-dns-mail postfix/smtp: C1102201234: to=<email@example.com>, relay=none, delay=2, delays=0.01/0/2/0, dsn=4.4.3, status=deferred (Host or domain name not found. Name service error for name=cjp-be.mail.eo.outlook.com type=A: Host not found, try again)
What could cause this, rather annoying, problem?