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!