In the current (old) system it is possible to define the body of the email and the content in the attached pdf based on the data in the invoicefile from the customer.
It is, however, not possible to change the subject of the email.
In the new api it would be very nice to be able to change the subject of the email based on various data in the email, like we can change all the other data in the content.
This is based on an actual request from customer who sends different layoutids from their system which defines language of invoice and whether the invoice is a reminder or regular invoice. This also defines if it is an invoice for membership or an invoice for services/goods.
Based on that they would like to have the subject read for instance:
I would suggest the functionality to have a default email subject as defined in the client - similar to the existing system - but then have the option to override that with code.