After creating the quote and with the quote open we select Email PDF from the Actions menu. This opens the email client within SuiteCRM.
The email account is defined in Admin/Email Settings with Users can send as themselves checked.
This was the only way I could make sending emails as a user work. All other ways I tried returned errors. I also never found good detailed documentation on all the different email settings so I left it at this setting.
We would have to search Github for any Issues already description this bug… but currently there are too many, and too disorganized, email issues there.
I think there could be a missing line setting the from name here: