So, I have made my own new invoicing system for the new tax year coming up and it works well. I generate the invoices in Excel and print to a PDF straight into Mail.app using the 'Save as PDF' button in the print dialog.
I'd like to be able to set up a smart folder with the sent invoices as they are easily identifiable with some search terms. It seems, though, that spotlight is not able to see into attachments which Mail.app has sent. The PDF information is part of an .emlx file within the Mail folder in my Library rather than a separate file.
Anyone got any ideas about this? Cheers.