Thread based on References header

Hi,
It would be great of Opera Mail could thread based on the "References:" mail header. Currently it seems to only use "in-reply-to", which leaves some threads detached because of the varying behaviour of the smorgasbord of mail clients across the world.

Specifically it would be great for me because of the behaviour of the "SMS Backup" android app that copies SMSes to an imap inbox with "References:" identical for each contact's messages (which is enough for GMail's web interface, for instance), but from my reading it seems some other "real" mail clients also do not use In-Reply-To and just use References (for instance, OE6).

Would be great if the M2 team could include this.

Cheers,
Jarrad

I think Opera supports both References and In-Reply-To. Would need to see the headers from the parent message and the messages that should be nested under it to see what's wrong.

Subject: SMS with MXXXXXX IXXXX
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
To: "MXXXXXX IXXXX" <+614XXXXXXXX@unknown.email>
From: jYYYYY.wYYYYYYY@gmail.com
Date: Sat, 15 Oct 2011 16:45:24 +1100
Message-ID: <d59401284dcd0f65774ef9260a7e1af4@sms-backup-plus.local>
References: <sl4qre0inb5stioy7mrdpqa7.586@sms-backup-plus.local>
X-smssync-id: 1181
X-smssync-address: +614XXXXXXXX
X-smssync-datatype: SMS
X-smssync-type: 2
X-smssync-date: 1318657524491
X-smssync-thread: 45
X-smssync-read: 1
X-smssync-status: -1
X-smssync-backup-time: 15 Oct 2011 05:50:25 GMT
X-smssync-version: 1404

Well you would be...just not at essays :)

Subject: SMS with MXXXXXX IXXXX
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
From: "MXXXXXX IXXXX" <+614XXXXXXXX@unknown.email>
To: jYYYYY.wYYYYYYY@gmail.com
Date: Sat, 15 Oct 2011 16:47:14 +1100
Message-ID: <38a0ffd05012c6defad44f971efcd82b@sms-backup-plus.local>
References: <sl4qre0inb5stioy7mrdpqa7.586@sms-backup-plus.local>
X-smssync-id: 1182
X-smssync-address: +614XXXXXXXX
X-smssync-datatype: SMS
X-smssync-type: 1
X-smssync-date: 1318657634682
X-smssync-thread: 45
X-smssync-read: 0
X-smssync-status: -1
X-smssync-protocol: 0
X-smssync-service_center: +61430004010
X-smssync-backup-time: 15 Oct 2011 05:50:26 GMT
X-smssync-version: 1404

:) 
i think i can live with that

The above two messages should be threaded (they are in GMail's web interface). In Opera, they are not.

Originally posted by Akdor1154:

The above two messages should be threaded (they are in GMail's web interface). In Opera, they are not.

Those two messages should be threaded under a parent message that has:

Message-ID: <sl4qre0inb5stioy7mrdpqa7.586@sms-backup-plus.local>.

Does the parent message have that message id? If it doesn't, then Gmail is just threading by subject or some other means probably.

Originally posted by http://tools.ietf.org/html/rfc2822#section-3.6.4:

The "References:" field will contain the contents of the parent's
"References:" field (if any) followed by the contents of the parent's
"Message-ID:" field (if any). If the parent message does not contain
a "References:" field but does have an "In-Reply-To:" field
containing a single message identifier, then the "References:" field
will contain the contents of the parent's "In-Reply-To:" field
followed by the contents of the parent's "Message-ID:" field (if
any). If the parent has none of the "References:", "In-Reply-To:",
or "Message-ID:" fields, then the new message will have no
"References:" field.

Though the contents of the field should as you state be a valid message ID, other implementations of threading (GMail, and I believe [though haven't got it installed to double check] Thunderbird, at least) simply require as above, that the child References contains a copy of the parent's References. There have been discussions about this elsewhere on the net, when I have a chance I'll research.

Could you show the headers for the parent message too? Or, are you saying that one of the two messages is the parent?

I imported the 2 messages into thunderbird and the second one is a nested under the first one (even if I import the second one first and the first one last).

So, in the case of Thunderbird, if the References headers are exactly the same (even if they just contain a single message id of another message (as in, not the message id of either message)), the one with the older date becomes the parent and the one with the newer date becomes the child. Does that describe what you're seeing in Gmail too?

Edit:
And, to clarify, in the case of more than 2 messages, the message with the oldest date becomes the parent and all the others are considered a reply to that parent.

neither of the two messages is the overall parent - as these are imported SMSes, the SMS exporter utility gives all messages from the same number the same References header for the purpose that threading mail agents would show them all in a single thread. One of the messages is in response to the other, but the parent here is child to another message in my inbox, etc.

The behaviour in Thunderbird you describe is what I'd like to see Opera do.

Originally posted by Akdor1154:

neither of the two messages is the overall parent - as these are imported SMSes, the SMS exporter utility gives all messages from the same number the same References header for the purpose that threading mail agents would show them all in a single thread. One of the messages is in response to the other, but the parent here is child to another message in my inbox, etc.

One more clarification:

Does that mean that in Thunderbird (if you were to use it), one of your sms threads would look like this:

- subject
    - subject
        - subject
            - subject
                - subject

where there's only ever one message under each level?

Or, would they be like this:

- subject
    - subject
    - subject
    - subject
    - subject

Or, would they be like this:

- subject
    - subject
    - subject
    - subject
    - subject

In testing, I think Thunderbird does it like that.

And, I double-checked just in case and the actual subject of the message doesn't matter (for thunderbird at least).

Since Opera doesn't support this, bug DSK-335159 is used to track this issue.

Thanks for reporting this and hopefully Opera will have this in the future.