How can you get user-initiated access to read their email? It seems there is OpenID, OAuth, OAuth2 and random other solutions.
The best I came up with so far is OAuth2 with scope=https://mail.google.com/.
Is there any permission that would just give me read-only access to the mail and ideally not scare the user with a permission notice like:
"View and manage your mail Perform these operations when I'm not using the application"
All I'd like, if possible "View your mail".
The GMail API documentation says there is only one scope giving access to everything.
There is also a feature called GMail Inbox Feed which could be what you want, but it is only available on Google Apps domains.