For opentaps Open Source ERP + CRM version 1.4, we have integrated the Ajax Web e-mail client from opentaps CRM with purchasing and financials, so now you can use it to send e-mails of your invoices:
and your orders, including both sales and purchase orders:
As well as use it to write e-mails to your contacts directly from opentaps. PDF’s for your invoices and orders are generated from opentaps automatically using jasper reports an attached to your e-mails.