Sent emails: invoices, credit notes, estimates, proposals and contracts now have a "Sent emails" card listing every time the document was emailed to the client: when, to whom, by whom, the attachments, and the message exactly as it was sent. Invoices also list their automatic reminders, recurring copies and payment confirmations.
Settings → Communication → Sent emails: administrators can see every email sent to clients about a document, filter by document type, client, date, status and whether it was sent by hand or automatically, open any of them, and remove entries.
Emails that could not be sent are kept too, with the reason, so you can see why a client never received a document.
