Probably every AX consultancy has programmed a module to send customer documents by email using addresses defined on the customer. With CU7 you can finally can do this in Standard AX:
Result: The e-mail is sent to the primary e-mail address defined on the customer.
The settings are now saved in the print destinations and do not need to be changed anymore. When the primary e-mail address is changed, the next e-mail will automatically be sent to the new address.
Even better, once the print settings have been saved, all sales orders will pick up their respective customer emails without further settings needed.
Follow the instructions here http://blogs.msdn.com/b/axsupport/archive/2013/02/05/emailing-customer-invoices-from-a-batch.aspx, you will be able to automatically send you confirmations and invoices by email using email addresses defined on the customer.
Select purpose in the print dialog: