Accessing Gmail emails through google app engine - google-app-engine

Question

How to get the e-mail contents by getting the user's login details in google app engine?

Answer 1

Try taking a look at the GMail API. You'll probably want to use OAuth.
https://developers.google.com/gmail/

Answer 2

This is exactly what I'm doing in my current project. Google App Engine Blog introduced a company named "Context.IO" and they provide very easy API to access GMail. I've implemented it in my project successfully.
Links
GAE Blog
Demo (You can look for a contact, and get all its emails...)
My Experience
They also provide a Explore feature that allow you to post and get json data from your gmail accounts.
However, if you registered for a free API key here, they will limit to 3 mailboxes per day. You can run a cron job to delete it daily. The nice thing is that you can contact them to get more mailboxes for development purposes :)
Hope my experience can help you

Answer 3

You can also use google service account. https://developers.google.com/identity/protocols/OAuth2ServiceAccount#creatinganaccount
Then you can use it in order to get access to account under your domain.
$client = new Google_Client();
$client->setApplicationName('My App');
$client->setAuthConfigFile('path/to/service_account.json');
$client->useApplicationDefaultCredentials();
// account that we want to check
$client->setSubject('account#mydomain.com');
$client->setAccessType('offline');
$client->setScopes([Google_Service_Gmail::GMAIL_READONLY]);
$service = new Google_Service_Gmail($client);
$messagesResponse = $service->users_messages->listUsersMessages('me');