Extend the functionality of posting a project invoice proposal with the possibility to send the project invoice as an electronic document during the posting. (just like you can select the option to print the document during posting)

With the current functionality a user has to post the invoice proposal and send the invoice as an electronic document afterwards.

This will particularly be useful in a situation where (project) invoices are posted and printed in batch.
You can't select the options to also send these invoices electronically so a user has to send these invoices afterwards manually.