How to delete unverified e-mail addresses in Firebase Authentication/Flutter?

Question

After registering with Firebase Authentication "Email / Password",saving e-mail without verification.I have application with Flutter firebase. When someone registers, I direct them to an email verification page and hold them there until they verify the email.The problem is that if someone uses my email and deletes app without verifying it, the mail still remains in the database.How do we delete unverified email addresses?

Answer 1

You can run a scheduled cloud function every day that checks for unverified users and deletes them. That also means you would have to use Admin SDK and cannot be done in Flutter. You can create a NodeJS Cloud Function with the following code and run it.

exports.scheduledFunction = functions.pubsub.schedule('every 24 hours').onRun((context) => {
    console.log('This will be run every 24 hours!');
    const users = []
    const listAllUsers = (nextPageToken) => {
        // List batch of users, 1000 at a time.
        return admin.auth().listUsers(1000, nextPageToken).then((listUsersResult) => {
            listUsersResult.users.forEach((userRecord) => {
                users.push(userRecord)
            });
            if (listUsersResult.pageToken) {
                // List next batch of users.
                listAllUsers(listUsersResult.pageToken);
            }
        }).catch((error) => {
            console.log('Error listing users:', error);
        });
    };
    // Start listing users from the beginning, 1000 at a time.
    await listAllUsers();
    const unVerifiedUsers = users.filter((user) => !user.emailVerified).map((user) => user.uid)

    //DELETING USERS
    return admin.auth().deleteUsers(unVerifiedUsers).then((deleteUsersResult) => {
        console.log(`Successfully deleted ${deleteUsersResult.successCount} users`);
        console.log(`Failed to delete ${deleteUsersResult.failureCount} users`);
        deleteUsersResult.errors.forEach((err) => {
            console.log(err.error.toJSON());
        });
        return true
    }).catch((error) => {
        console.log('Error deleting users:', error);
        return false
    });
});

Answer 2

This works just perfect:

const functions = require("firebase-functions");
const admin = require("firebase-admin");

admin.initializeApp();
exports.scheduledFunction = functions.pubsub
  .schedule("every 24 hours")
  .onRun((context) => {
    console.log("This will be run every 24 hours!");
    var users = [];
    var unVerifiedUsers = [];
    const listAllUsers = async (nextPageToken) => {
      // List batch of users, 1000 at a time.
      return admin
        .auth()
        .listUsers(1000, nextPageToken)
        .then((listUsersResult) => {
          listUsersResult.users.forEach((userRecord) => {
            users.push(userRecord);
          });
          if (listUsersResult.pageToken) {
            // List next batch of users.
            listAllUsers(listUsersResult.pageToken);
          }
        })
        .catch((error) => {
          console.log("Error listing users:", error);
        });
    };
    // Start listing users from the beginning, 1000 at a time.
    listAllUsers().then(() => {
      unVerifiedUsers = users
        .filter((user) => !user.emailVerified)
        .map((user) => user.uid);
      admin
        .auth()
        .deleteUsers(unVerifiedUsers)
        .then((deleteUsersResult) => {
          console.log(
            `Successfully deleted ${deleteUsersResult.successCount} users`
          );
          console.log(
            `Failed to delete ${deleteUsersResult.failureCount} users`
          );
          deleteUsersResult.errors.forEach((err) => {
            console.log(err.error.toJSON());
          });
          return true;
        })
        .catch((error) => {
          console.log("Error deleting users:", error);
          return false;
        });
    });
  });

Answer 3

You can delete users through the Firebase Admin SDK.

You'll need a list of unverified users, either by listing all users and filtering it down, or from somewhere you store this yourself, and then you can delete the unverified users.