To get a user ID by email in WordPress, you can use the get_user_by function. Here’s a basic example of how to do it:

$email = 'user@example.com'; //The email address you're searching for

$user = get_user_by('email', $email);

if ( $user ) {
  $user_id = $user->ID;
  echo 'User ID: ' . $user_id;
} else {
    echo 'User not found';
}

Replace user@example.com with the email address you are looking up.

get_user_by('email', $email) retrieves the user object based on the email.

If user is found $user->ID provides the user ID.

If no user is found with that email, it will output “User not found”.