well, I try to send email via google 'aspmx.l.google.com' server, port 25. I can send emial, technically. I just have to wait one minute to wait the sending process complete.

Then I try to do telnet to aspmx.l.google.com from my terminal and I found that it tries ipv6 first and then tries ipv4 after ipv6 is timeout.

I believe that is why I need to wait a minute for sending email.

BTW: I am doing it locally.

Does anyone know what is the real problem and how to fix it?

Thanks in advance

closed as not a real question by Ward - Reinstate Monica, Dave M, Rex, mdpc, Dennis Kaarsemaker Jun 11 '13 at 17:12

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Sorry to answer your question with questions...

Which IPv6 address is it returning? Same as I get?

aspmx.l.google.com. 293 IN AAAA 2a00:1450:4013:c00::1a

Can you force ipv4 for your email server instead of trying to use ipv6 to verify that this is really your issue? Does your mail log's timestamps show a one minute delay even with ipv4 forced?

See here if you are using Postfix: http://linuxmoz.com/google-mail-ipv6-network-is-unreachable-postfix-ipv4-only-fix/

  • if I try: 'telnet aspmx.l.google.com 25', I wll get 'Trying 2607:f8b0:400d:c00::1b...', after 1 minute, it will try '', then it works – Jerry Meng Jun 11 '13 at 14:12
  • Are you using postfix? Can you force ipv4 in your email server and see if it doesn't delay 1 minute? – TheCleaner Jun 11 '13 at 14:15
  • I am not using postfix. By forcing use ipv4 is exact what I want. Actually, the point is that I am developing locally and running it somewhere at AWS instance. On the AWS instance, it is fine. So somehow I can just leave with it locally. However, we just want to know why, on my local machine, it will try ipv6 first than try ipv4. – Jerry Meng Jun 11 '13 at 14:19
  • If you have ipv6 enabled on your local computer since Google supports ipv6 it will try to resolve/connect using ipv6 first. You can disable ipv6 on your local machine to verify/test if you want. – TheCleaner Jun 11 '13 at 14:22
  • 1
    I seems know how to solve it, just uncomment precedence ::ffff:0:0/96 100 in my /etc/gai.conf file. – Jerry Meng Jun 11 '13 at 14:25

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