Feature Request: Document-dependent "from" email address

I'd like to request being able to set an email from address on the document level. This would allow you to set a from email address depending on the document type.

Eg.

Your purchase orders are sent from purchasing@yourcompany
Your order confirmation emails are sent from sales@yourcompany
Your invoices are sent from accounts@yourcompany

At present you can only send via the logged-in user or a company-wide email. This would allow you to have replies come to the relevant company department.