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Tasklist

FS#33754 - gerolde.archlinux.org has wrong ipv6 PTR for delivering mail

Attached to Project: Arch Linux
Opened by James Cloos (cloos) - Thursday, 07 February 2013, 17:15 GMT
Last edited by Dave Reisner (falconindy) - Thursday, 07 February 2013, 17:37 GMT
Task Type Bug Report
Category System
Status Closed
Assigned To No-one
Architecture All
Severity Medium
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

Description:

Best Practices for email delivery include ensuring that the PTR RRs for the IP addresses used for outgoing SMTP sockets resolve back to the name specified in the HELO/EHLO messages.

Even though gerolde.archlinux.org only has an A record, it makes outgoing connections from the v6 address 2001:0470:1f10:0717::2, which has a PTR of:

archlinux-1-pt.tunnel.tserv9.chi1.ipv6.he.net.

That discrepency can and does prevent email delivery.

Arch needs either to:

Ask HE to change that PTR to gerolde.archlinux.org

Get a block from them, point it at your own nameserver set the PTR
and use a src specification in the ip(8) route command

Try adding 'precedence ::ffff:0:0/96 100' to /etc/gai.conf

Or tell everyone on the mailing lists to whitelist 2001:0470:1f10:0717::2.

Otherwise delivery over ipv6 will more often fail then succeed.


Additional info:
* package version(s)
* config and/or log files etc.


Steps to reproduce:
This task depends upon

Closed by  Dave Reisner (falconindy)
Thursday, 07 February 2013, 17:37 GMT
Reason for closing:  Not a bug
Comment by Dave Reisner (falconindy) - Thursday, 07 February 2013, 17:37 GMT
Best practices or not, RFC 2821 states that a mismatch in the EHLO and the actual sender is not a valid reason to block a message. From http://www.ietf.org/rfc/rfc2821.txt:

An SMTP server MAY verify that the domain name parameter in the EHLO
command actually corresponds to the IP address of the client.
However, the server MUST NOT refuse to accept a message for this
reason if the verification fails: the information about verification
failure is for logging and tracing only.

Therefore, only broken hosts are blocking delivery of our mail.

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