Reflect Invoice No. or Purchase Order No. in subject when emailing from Reckon

Often when we email our purchase orders/invoices from Reckon the client will respond to our email and we have NO idea what invoice/purchase order they are referring to as the subject line only says "Purchase Order sent from ……….." or "Invoice sent from………". It is very annoying as several of us share the same email address and we don't know which purchase order or invoice they are referring to. Is there any way when we email from Reckon the system can put the invoice/purchase order number in the subject line when sending????