Thank you for this reply.  I'm a real estate photographer and need to display a unique address of the listing property in the subject line of every invoice.  I've been c/p the addresses in manually but my clients do not see those pasted address for some reason.  Instead of [Invoice Number] is there another field that can pull into the subject line such as [Note} or [Special] or something?  To be clear, I need one invoice to read: Invoice from [Business Name] from 1234 Oak St, then my next invoice would be Invoice from [Business Name] from 777 Sunny Way Dr