How to get google ID from email
First of all you should store the email property always in lowercase since the case is not relevant. Now if you also want to take into the account the dot or the plus symbols and being able to query on them, you should then store in another (hidden) property the stripped out version of the email and execute your queries on this one.
I'm using google ID as the datastore id for my user objects.
Sometimes I want to find a user by email. The gmail address can appear with dots or without, capital letters and other variations. How can I retrieve the user id from the given email?