My organization has a Survey123 survey that is shared with a specific group in our ArcGIS Online organization. There are dozens of people with whom the survey has been shared, but we now need to reach out to them to inform them of a change to the survey. Not all of the members of the group are members of our ArcGIS Online organization; the group contains members from outside organizations.
From looking at the Python API, we suspect it is possible to get a list of all the group members who are members of the organization, but not the folks who are not in the org.
Is it possible to get a list (including email contact information) for group members who are both inside and outside of our ArcGIS Online organization?
I think you are right in stating that it is not possible to retrieve the email addresses of members of a group who are not member of your organisation.
Recently I wrote a script to get an overview of group membership in an AGOL organization, but I had to jump over all group members outside the organization to avoid the error message
See the link below for the script (which does not solve your issue):
Curious what the solution would be.