With the keyconfig extension you can attach little scripts to keyboard shortcuts. It took me quite some googleing to find the right commands for moving the selected message to a specific folder:
- Download and install keyconfig
- Right-click on your destination folder (here: SPAM) and choose "Prefences"
- Copy the address of the folder (here:
imap://koem%40blabla.de@capella.uberspace.de/SPAM) - Open the Add-Ons-Manager and choose Prefences of keyconfig
- Create a new shortcut and paste this as the code:
MsgMoveMessage(MailUtils.getFolderForURI("<the-copied-folder-address>")); - Name it, save it and assign a keyboard shortcut