I really like mail.app from Panther (OS X 10.3): standard mbox storage, clean aqua look, life is good.

Mail.app in 10.4 rubs me the wrong way - so much so that I won't use it. I've tried copying mail.app from an old Panther installation, but it doesn't open. I see the "icon zooming bigger" animation, and then nothing happens. I'm still in the Finder.

Is there a way to run mail.app v1.3.11 in Tiger?

Trying to run old software on a newer OS will only lead to pain.

Embrace change (it's what keeps your brain young). The solution is to become less sensitive to the way you're rubbed. Use the newer Mail.app for a week and you'll learn to love it just as much as the old one. It's really much better.

If you will be updating to Leopard, the mail app will be updated again and should be a big improvement. You will finally be able to designate a default email account for outgoing emails.

You can do that now in Mail under Tiger (at least for new messages).

In Mail->Preferences->Composing there's an item for "Send new mail from:".

Otherwise, the default for replies is the address the original was sent to.

Regardless, I look forward to Leopard and improvements everywhere. I suspect, however, that someone who took this long to switch to Tiger isn't going to be one of the first to update to Leopard.