Cannot send mail with exim4 to gmail
 

Hi,
I recently had some issues with sending emails with exim4 (mutt or mail commands) to gmail accounts. This is the error log I get when trying:

"This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

lorenzo.cozzi1@gmail.com
host gmail-smtp-in.l.google.com [2a00:1450:400c:c09::1b]
SMTP error from remote mail server after pipelined end of data:
550-5.7.1 [2001:760:2c05:1019:2d8:61ff:fe2e:adc3] Our system has detected that
550-5.7.1 this message does not meet IPv6 sending guidelines regarding PTR
550-5.7.1 records and authentication. Please review
550-5.7.1 https://support.google.com/mail/?p=IPv6AuthError for more information
550 5.7.1 . e8si26543251wrj.94 - gsmtp"

Someone knows how to fix it?

My computer has Debian testing installed with kernel 4.20.0-trunk-amd64.

Thanks in advance,
Lorenzo

They give you a link that talks about it. Did you review what is at that link?

In short, many organizations reject email that comes from an address that doesn't have a specific reverse IP "PTR" record in DNS. When I check here and at DNS Stuff it says you have no record for the IPv6 address, 2001:760:2c05:1019:2d8:61ff:fe2e:adc3, listed in the error output.

The DNS Stuff lookup can be done at:
https://tools.dnsstuff.com/#reverseD...61ff:fe2e:adc3

Another link with same error and discussion on how to fix:
https://support.plesk.com/hc/en-us/a...ng-PTR-records

I tried but I couldn't manage to solve the issue. Disabling ipv6 in exim4 would solve the problem, but simply adding 'disable_ipv6 = true' to its config file and restarting the service didn't work. Do you have any clue about how to correctly do it?

I don't use Exim myself. This link suggests there should be no spaces so it should be:
You appear to have put spaces before and after the equal sign.

Did you run the netstat command listed in above link to be sure it isn't LISTENing on IPv6 after the restart?

Note that you might still run into the rejection when using IPv4 if you have no PTR for your outbound IPv4 IP. Did the message from Gmail change after you restarted?

I tried what suggested in the link you provided and added the string:
in the exim4.conf.template file stored in root@host:/etc/exim4 folder.
Now the ipv6 is disabled and I managed to send emails to my gmail address.

Thanks a lot for the help!