Add "Send dunning letters by email" to Customer endpoint

[Anonymous]

Request:

Add "Send dunning letters by email" to Customer endpoint

Story:

The basis for invoices and customers are created in pre-system and invoices and customers generated in Visma.net based on that.

A customer cannot be created without an email address, if the options "Send dunning letters by email" and "Send dunning statements by email" are ticked. The customer need these boxes ticked if there is an email address and not ticked if it' missing. Users needs API to support this.

UI: