Mail threads are mixed up what do I do?

I have exactly the same issue, and its driving me nuts!

I also have the exact same issue since upgrading to Yosemite

An absolute nightmare and disgrace for theses issues to keep happening with upgrades.

i have the same problem - even when you cut and paste an email address into the search box the results are a mix with often 10 different emails being grouped into one. Come on apple sort this out.

I'm not sure how to properly submit a bug report but I've noticed this about mixed messages in the Mail threads...

If you view the Raw message (View->Message-Raw Source)

in the "References:" section there are a series of identifiers looking something like...

<0FA100E1002C504EA922B8279AE2998D0133654BB1@someAddress.com>

<E2274F86-B383-4459-B71D-E2B380B85C97@anotherAddress.com>

with only the mail messages that are mixed together there are unusual identifiers that look like...

<,<0FA100E1002C504EA922B8279AE2998D0133654D32@someAddress.com> <>>

notice the extra "<," and trailing "<>>"

on threads that work correctly I do not notice this. I'm not sure if this is indeed the problem or of anyway to fix it, but perhaps this may get seen by someone with more insight and can bump us along to a fix.

Problem still happening Dec 17, 2014, and no response from Apple. Awesome.

More info: I tried Mailbox -> Rebuild, and that didn't fix it, and I deleted the Envelope Index files and restarted Mail. No luck.

Anyone find a workaround?

I'm still experiencing this issue, and its making my daily work a living nightmare, its impossible to find info in a specific email conversation when there's other emails from other customers showing up in the same conversation view.

It's now a week into the new year 2015.

Yet, we are still having the 'mixing threads up (emails from different people about different topics are mixed up with other threads which are not related)'

Apple, please help!

Agree, none of this would be happening if Steve Jobs was still about, its as if Apple is getting worse since his passing.

This is driving me nuts. Not only threads and people get mixed up, also different e-mail accounts I have also got mixed up. I open a thread to see other threads, other people as well as emails from other email accounts. C'mon Apple !

I'm having the same problem. Very difficult to keep straight. Need help here!

So, Apple is not responding, and it's obviously broken.

Does anyone have an alternative mail client, even paid? Some people use Outlook in the office, but that's a bit heavy. Anyone else have alternatives they've used successfully? Even paid would be OK if it worked.

Same problem here too. The threads seem to have no relation to each other. Headings aren't even similar, nor are the subjects discussed nor the recipients. It didn't start doing this until a week ago, even though I've had Yosemite for a month or more.

I am experiencing the same problem and it is forcing me to work in gmail online, which I don't like, but I am getting used to.

Apple, hurry up!

+1 on this.

I'm still experiencing this issue since my last post here in November last year. How can we report directly to Apple? Apple don't check on here strangely enough I'm told.