I was using XP before, using Outlook 2007 to compose the emails not Word. It definitely used to open new email windows with the taskbar button at the far right of all taskbar buttons. Thanks for looking.
I don't know what to tell you, but I think it has something to do with the Taskbar previews. When multiple windows are open from the same program, the Taskbar Previews all have to show up grouped in one area. Even if you have Aero completely disabled, you still get a pop-up when you hover over a Taskbar button. So if you could find a way to have an Outlook Window here, an e-mail over there, and then another e-mail
way over there, hovering over one of them would pop up a preview for all 3 in their individual separate spots. I don't know about you, but I think that would irritate me. I would want to disable Taskbar Previews entirely, but I use them to close windows by middle-clicking the preview.
I quite like the organization: I have Outlook pinned to the Taskbar in position #3. So, I open it with Windows Key + 3 (Windows Key + 0 opens up the 10th pinned item from the left), and then I can open a handful of e-mails and they all get organized right there. It's kind of like my little e-mail center.
The same goes for every program I have pinned: any new windows that open go right next to it so that they all stay together instead of getting lost in between other Taskbar buttons. Then of course the program and all of its windows can be dragged around to different places on the Taskbar.
Of course, an item doesn't have to be pinned in order for it to work that way, but I have certain programs pinned so that they're always in the same place every day. That way when I have a ton of e-mails opened with 10 other widows open for other things, I don't have to try to remember where my e-mails are: they're all right there in that one spot.
I realize though that the XP way of doing things was useful for knowing approximately when you opened a window, but I think that this behavior was completely taken away due to the Taskbar Previews.
Take Windows Explorer for example: you can open 20 different folders, but they're all going to stay together as a group because Windows Explorer is one program. So, the same goes for any program: if the program opens more than one window, then it will stay with the program. You can even try moving one around and the whole group moves as one unit because it's one program.
I understand though that this doesn't help when you were previously able to get a basic idea of when you opened something based on where it's located on the Taskbar. However, I haven't run into that problem yet. I don't know if I've adjusted or what, but I just haven't run into that problem yet.
So combined or not, multiple Taskbar buttons for one program have to be grouped.