URL to compose a message in Gmail (with full Gmail interface and specified to, bcc, subject, etc.)
This seems to work (for now): https://mail.google.com/mail/?view=cm&fs=1&to=someone@example.com&su=SUBJECT&body=BODY&bcc=someone.else@example.com
google-apps
Error: invalid_client no application name
That error is displayed in case that under “APIs & auth” -> “Consent screen” you have empty field “PRODUCT NAME” – you need to select e-mail address as well. You can find “Consent screen” under a link!, click on project name and then go to “APIs & auth” -> “Consent screen”.