I installed the Microsoft's Windows Live Mail Desktop Beta the other day. From what I can tell, it's sort of a free successor to Outlook Express to access Windows Live Mail (the online web based version that's succeeding the Hotmail brand name) and other IMAP/POP accounts and RSS feeds from desktop software. There will also be Windows Mail included with Vista, also I believe based on Outlook Express, but different again (no duplicated effort or confusing marketing names there!... *sigh*)
Anyway, here's the interesting bit. With the message list, there's a little envelope icon in the left hand column, but when you move the mouse over the row, the envelope icon turns into a checkbox. To select that email, you can click on the checkbox. So then if you want to select multiple emails, rather than having to hold down the CTRL key and click each email, you can just move down the list, clicking on each checkbox. This is exactly like most webmail systems (including FastMail) do it!
Now head on over to the new ajaxy yahoo mail, and you'll see they've tried to copy the old behavior of most email clients where to select multiple emails you have to hold down CTRL to select multiple emails, or SHIFT to select a range.
Ironic isn't it, we've got webmail people trying to copy the desktop email interface in webmail clients, and the desktop email software people trying to copy the webmail interface in desktop email clients.
Discussing this the other day with some people, I can see why the webmail approach might actually be better. At a guess, 80% of computer users probably don't actually know that holding CTRL will allow a multiple disjoint selection in standard multiple-selection list environments. Additionally, if you forget to old down the CTRL key just once, you'll loose everything you selected and be back to a single selection. I find that often even happens to experienced users and it's damn annoying. Having checkboxes to "hold the state" of a selection seems pretty useful to the average user.
So will this change over spread to other clients? I haven't installed Windows Vista, but have a look at Windows Mail again. From the screenshot there:
It appears to have a checkbox column as well, so it seems both the standard "basic" email programs from Microsoft (e.g. not Outlook) are now cloning the webmail interface more. I wonder how long it will be before other developers that have spent so long trying to clone the Outlook/Outlook Express interface in a webmail client will start changing back.