Invoice "Date sent"

This will answer the question when Invoice "Date sent" is set automatically and when user need to put it manually.

Status Invoice sent is changing when is set Invoice field "Date sent"

Send invoices values

By e-mail (with POD)*
By post (with POD)
By e-mail and post (with POD)
Don't send (Self-billing)*
Download in client portal*
By e-mail (invoice upon delivery, second time with POD)
By e-mail (without POD)*
Upload to the customer portal together with POD*