Crosspost from this thread. Feel free to add yours!
=== begins reposting ===
Another tip to import only selected mailboxes in the front window. This is handy if you have zillions of mails and don’t want to import them all. Open [color=red]_Mail Import.scpt file inside Addressbook & Mail in your DT script folder and change the last part (the tell block below [color=red]exportMailboxToDEVONthinkPro) to:
tell application "Mail"
set selectedMailboxes to selected mailboxes of front message viewer
repeat with theMailbox in selectedMailboxes
tell application "DEVONthink Pro" to hide progress indicator