Thursday, June 11, 2020¶

On luc@laudate I said:

$ echo "body" | mail -s "test 20200611" luc.saffre@gmx.net tonis.piip@gmail.com luc@saffre-rumma.net

and here are the responses from three different providers:

to=<luc.saffre@gmx.net>, relay=mx01.emig.gmx.net[212.227.17.5]:25,
status=bounced (host mx01.emig.gmx.net[212.227.17.5] said: 550-Requested action
not taken: mailbox unavailable 550 invalid DNS MX or A/AAAA resource record (in
reply to MAIL FROM command))

to=<tonis.piip@gmail.com>,
relay=gmail-smtp-in.l.google.com[2a00:1450:4010:c06::1a]:25,
status=bounced (host
gmail-smtp-in.l.google.com[2a00:1450:4010:c06::1a] said: 550-5.7.1
[2a01:4f9:c010:9a4f::1] Our system has detected that this message does 550-5.7.1
not meet IPv6 sending guidelines regarding PTR records and 550-5.7.1
authentication. Please review 550-5.7.1
https://support.google.com/mail/?p=IPv6AuthError for more information 550 5.7.1
. s9si1542418ljg.411 - gsmtp (in reply to end of DATA command))

to=<luc@saffre-rumma.net>, relay=mail.saffre-rumma.net[167.114.252.122]:25,
status=bounced (host mail.saffre-rumma.net[167.114.252.122] said: 504 5.5.2
<luc@laudate>: Sender address rejected: need fully-qualified address (in reply
to RCPT TO command))

Three different messages to the same mail. The third error is the most helpful here because it says <luc@laudate>: Sender address rejected. IOW our postfix did not convert the local domain “laudate” into the fqdn “laudate.ee”. I guess that this is the main problem.

Furthermore, when I specify the from: header myself, it works:

$ echo "body" | mail -s "some test" -a From:luc@laudate.ee luc.saffre@gmx.net tonis.piip@gmail.com hamza@saffre-rumma.net

Except that it doesn’t because it hits a next problem:

Jun 11 18:38:08 laudate postfix/smtp[10449]: D18143FFEE: to=<luc.saffre@gmx.net>, relay=mx01.emig.gmx.net[212.227.17.5]:25, delay=0.52, delays=0/0.02/0.24/0.25, dsn=5.0.0, status=bounced (host mx01.emig.gmx.net[212.227.17.5] said: 550-Requested action not taken: mailbox unavailable 550 invalid DNS MX or A/AAAA resource record (in reply to MAIL FROM command))

550 invalid DNS MX or A/AAAA resource record¶

Another problem was that Thunderbird now gave me this error message when sending to tonis@laudate.ee:

An error occurred while sending mail. The mail server responded: Requested action not taken: mailbox unavailable invalid DNS MX or A/AAAA resource record. Please check the message recipient “tonis@laudate.ee” and try again

Same when sending to luc@saffre-rumma.net or to luc@lino-framework.org. These seem to be caused by the fact that we changed th MX records of our servers from FQDN to mail.FQDN.

I read a blog post in German, which complains that GMX refuse to accept incoming mail when the MX server of the recipient has no A/AAAA record. Indeed we did not have an A record for mail.SR, we “only” had a wildcard CNAME that points to SR itself. This should theoretically be enough. But above blog post made me try to also add an A record for mail.SR (which of cours points to the same IP as SR itself). And –miracle!– it it made the TB error disappear. TIL : it seems that the domain given by the MX record (the FQDN of our mail server) needs to have its separate A record. Just a CNAME is not enough for a mail server.

Unauthenticated email from xxx is not accepted due to domain’s 550-5.7.26 DMARC policy¶

We also saw this reply:

relay=gmail-smtp-in.l.google.com[2a00:1450:4010:c06::1b]:25,
status=bounced (host gmail-smtp-in.l.google.com[2a00:1450:4010:c06::1b] said:
  550-5.7.26 Unauthenticated email from laudate.ee is not accepted due to
  domain's 550-5.7.26 DMARC policy.
  Please contact the administrator of laudate.ee domain 550-5.7.26 if this was
  a legitimate mail. Please visit 550-5.7.26  https://support.google.com/mail/answer/2451690
  to learn about the 550 5.7.26 DMARC initiative.