Hello Andrea, You can find details relevant to your question "what is a google-hosted domain account" on the "Mail API Overview" documentation page <https://cloud.google.com/appengine/docs/standard/go/mail/#who_can_send_mail>, namely in the "Who can send mail" sub-chapter.
"App Administrators can add the following accounts to the list of Authorized Senders: Their own email address Any group for which they are an Owner or Manager Applications hosted in a G Suite domain: noreply@[DOMAIN].com, as long as noreply@[DOMAIN].com is a valid account (user or group)". -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/google-appengine. To view this discussion on the web visit https://groups.google.com/d/msgid/google-appengine/b8610c73-f792-487a-8f2b-9821aa3177f6%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
