code: func (manager *Manager) GetValidatedEmailAddressesByUsernames(usernames []string) (validatedEmails []ValidatedEmailAddress, err error) {
  	mgoCollection := db.GetCollection(manager.session, mongoValidatedEmailAddresses)
  	qry := bson.M{
  		"username": bson.M{
  			"$in": usernames,
  		},
  	}
  	// Avoid returning multiple email addresses for the same user
  	err = mgoCollection.Find(qry).All(&validatedEmails)
  	return
  }
docs: // Returns all validated email addresses for every username