Sends an estimate to the deal's contact. For a draft, this marks the estimate sent (setting sent_at, and valid_until from the company's default validity period when you have not set one), saves a PDF copy to the deal's documents, and emails the PDF. For an estimate that is already sent, it emails the PDF again without changing the estimate.

The email is only sent when the contact has an email address and has not opted out of email. The estimate is still marked sent when it cannot be emailed, and message says why it was not delivered, so show it to the user.

Estimates that are accepted, declined or void cannot be sent. The token's role must be allowed to prepare estimates, and must either have access to all records or be the sales rep assigned to the deal.