Answer mail is treated as new thread when sent with Outlook

[leonex-cs1]

Hi,
today I have sent an answer mail to the topic "[RFC] [VOTE] Typed properties v2" started 9 days ago by Bob Weinand. But anyhow #externals shows it as a new independant topic.

Can you tell me why this happened? What made I wrong?

I am using Outlook as mail client.

[mnapoli]

Thanks for opening this issue, that happens from time to time with some emails. Maybe it's your email client, maybe something else 🤔

Here is the code that builds threads. It works by reading the References header:

externals/src/EmailSynchronizer.php

Lines 160 to 172 in a50d410

	// Reply to
	$threadId = $emailId;
	$inReplyTo = null;
	$references = $parsedDocument->getHeaderValue('references');
	if ($references) {
	$references = preg_split('/(?<=>)/', $references);
	$references = array_filter(array_map('trim', $references));
	// Take the last item (the direct parent)
	if (! empty($references)) {
	$threadId = reset($references);
	$inReplyTo = end($references);
	}
	}

Here is an example of an answer to the same thread that was correctly recognized: https://externals.io/email/103180/source (it has the References header)

Your email doesn't have that header: https://externals.io/email/103192/source

(FYI you can view the source of each email by clicking the "view source" link on externals.io)

I have no idea how to help further. Are you replying by email, or are you using the NNTP protocol?

[leonex-cs1]

It looks like Outlook uses its own proprietary way to sign references (see https://stackoverflow.com/a/4621303/1119601). It uses the Thread-Index and Thread-Topic headers.

For those wanting to know internals of the Thread-Index header, it is a Base64 encoded string. The first 22 bytes are the original unique portion and each reply adds an additional 5 bytes on to it. We only use the first 22 bytes to identify the email.

Maybe #externals once will be able to support those headers, too 😉 Mit freundlichen Grüßen aus Paderborn Christian Stoller Web-Entwicklung LEONEX Internet GmbH Technologiepark 6 33100 Paderborn Tel: +49 (5251) 4142-526 Fax: +49 (5251) 4142-501 HRB 8694 AG Paderborn Geschäftsführer: Stephan Winter

…

________________________________ LEONEX ist umgezogen: Bitte beachten Sie unsere neue Adresse sowie unsere neuen Rufnummern. Wann dürfen wir Sie in unsere neuen Räumlichkeiten einladen?

________________________________ Von: Matthieu Napoli <notifications@github.com> Gesendet: Donnerstag, 20. September 2018 14:12 An: mnapoli/externals <externals@noreply.github.com> Cc: Christian Stoller <Christian.Stoller@leonex.de>; Author <author@noreply.github.com> Betreff: Re: [mnapoli/externals] Answer Mail is treated as new Topic (#96) Thanks for opening this issue, that happens from time to time with some emails. Maybe it's your email client, maybe something else 🤔 Here is the code that builds threads. It works by reading the References header: https://github.com/mnapoli/externals/blob/master/src/EmailSynchronizer.php#L160-L172 Here is an example of an answer to the same thread that was correctly recognized: https://externals.io/email/103180/source (it has the References header) Your email doesn't have that header: https://externals.io/email/103192/source (FYI you can view the source of each email by clicking the "view source" link on externals.io) I have no idea how to help further. Are you replying by email, or are you using the NNTP protocol? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub<#96 (comment)>, or mute the thread<https://github.com/notifications/unsubscribe-auth/AJ9sY-2whAjI-wmLxBojrhakhGxPiFVSks5uc4X2gaJpZM4Wx9As>.

[mnapoli]

Sure, I won't work on that myself but if you have time for a pull request I'd gladly merge it!

[lpd-au]

Recently there's been a flood of threads collapsed into individual messages, such as the Decoding HTML and the Ambiguous Ampersand thread that appears to have so many parts, it's impossible to search for them all (limit appears to be 10 threads?). Is this the same cause; did the whole list switch to using Outlook? It's making the site unusable :(

[mnapoli]

@lpd-au I'd suggest two things:

• listing explicit examples here so that others can investigate further
• or investigating directly what is going wrong, then we can discuss a potential fix (if we can)