[neilw]

The new threaded view in Panther Mail is very nice, but it comes with one major caveat: Mail seems to determine what constitutes a thread solely by the Subject line. It is therefore very easy for unrelated messages with the same subject to get lumped into the same thread. This can bite you when deleting a thread (there may be things in there you don't want to delete) or, if you don't have all threads expanded, it can hide some messages that you want to see.

This took me by surprise because I'm accustomed to threaded newsreaders that are able to more effectively determine what constitutes a thread, and I expected Mail to work the same. Now that I think about it some more, it may be that emails do not actually have enough info in them to do this properly, so it may not even be possible.

In any case, beware.

[Developer]

Not true. I have seen threads change the subject line several times and Mail correctly (magically?) displays them together.
I have also seen mails with the same subject line of the same thread erroneously displayed separately.

[neilw]

Interesting. I guess there's an algorithm in there trying to do what it can.

I do know that I have *definitely* seen unrelated messages with the same subject line lumped under the same thread.

I hold to my warning, though, not to depend on threaded view being perfect. It'd be very easy to get lazy and assume it's always working correctly.

[Earth Mk. II]

It probably checks the mail headers for the In-reply-to: <origional message id> and Message-id: fields first, then tries subject matching or something if that's not there.

But what can happen is, if you hit "reply to" in your e-mail client and then write a completely new message (deleting any quoted stuff), the In-reply-to: field will be inserted into the header by the sending client, making mail think it's related to another topic - when it's really not.

At least, that's what I'm assuming is happening based on the behaviour I'm seeing and looking over the raw source of messages.

[CatOne]

Originally posted by Earth Mk. II:
It probably checks the mail headers for the In-reply-to: <origional message id> and Message-id: fields first, then tries subject matching or something if that's not there.

But what can happen is, if you hit "reply to" in your e-mail client and then write a completely new message (deleting any quoted stuff), the In-reply-to: field will be inserted into the header by the sending client, making mail think it's related to another topic - when it's really not.

At least, that's what I'm assuming is happening based on the behaviour I'm seeing and looking over the raw source of messages.

It is definitely checking the reply to information... there is thread information contained in the messages.

Regarding your comment about "reply to" -- I'd argue that mail is doing the right thing here. Someone is following up to a message, and changing the subject. It may have nothing to do with the original message (causing issues on mailing lists), but really shouldn't the person start a new message and send it to the list, rather than reply to a message and change the subject? It's really "user error" -- they're doing it that way because it never *used* to cause anything weird to happen.

Using thread ID's to track threads is the *right* way to do things, because it's exact.

Though yes mail *does* group things by subject, if the emails don't have any other associated thread information. This can be confusing, and maybe it shouldn't do this. Or it should be configurable to not do this.

[Scifience]

The subject line must be a main factor, since the order confirmation Apple sent for Panther got threaded in with the order confirmation for the iSight I just ordered. Same subject line, yes, but dealing with two unrelated issues and over two weeks apart in date.

I've also had this happen with PayPal notifications ("Receipt for online purchase") and eBay stuff. Annoying.

[Thor]

The subject line must be a main factor, since the order confirmation Apple sent for Panther got threaded in with the order confirmation for the iSight I just ordered. Same subject line, yes, but dealing with two unrelated issues and over two weeks apart in date.

Both order confirmations had the same "Reply-to". (noreply@store.apple.com or similar)

[clarkgoble]

Originally posted by CatOne:
but really shouldn't the person start a new message and send it to the list, rather than reply to a message and change the subject? It's really "user error" -- they're doing it that way because it never *used* to cause anything weird to happen.

I might buy that if threaded mailing was common. It's not. There ought to at least be an option to ignore messages with different subject lines. (I don't know if this is how Mail does it since I don't use threading)

[real]

Is there anyway of manualy moving the message(mail) to the correct thread.
thanks

real