On 26/04/2006, at 5:05 AM, Andrew in the WAMUG Mailing List digest wrote:

My wife has around 500 read e-mails she wants to keep. It might be
unrelated, but it's taking longer to open Mail and I thought this
would un-clutter it and help it open quicker.

10.3.9?  That's a snack to do.
Here's my lazybones recipe:

Make a mailbox called something that shows it's for emails you want to keep.
Drag the ones you want to keep in there.
Regularly - depends on the volume for me but you could have one labelled for each month, year etc - drag that mailbox into where you want to keep it separate from Mail. Voila, a mailbox that has a unique name and which will open with a double-click in Mail, but only when you want it to.
Then you can delete its original.

Nancy M