If the external database doesn't have user e-mail, how should Moodle know it needs to go to Google?
Anyway, there is a full forum on Authentication. Also use the Advanced search facility for similar discussions. Saw this discussion, Authenticating user on third party website using Moodle, by chance (oddly in the General developer forum).
Anyway, there is a full forum on Authentication. Also use the Advanced search facility for similar discussions. Saw this discussion, Authenticating user on third party website using Moodle, by chance (oddly in the General developer forum).