To stop users signing in to WordPress with an email address while keeping username login, add a small callback to the authenticate filter. The example below rejects email-shaped login identifiers and lets ordinary usernames continue through WordPress’s normal authentication flow.
How WordPress email login works
WordPress’s standard login accepts either a username or an email address; its login guide labels the field “Username or Email Address.” WordPress Developer Resources: Logging In.
When authentication runs, WordPress applies the authenticate filter. Its wp_authenticate_email_password() callback handles email-and-password authentication, while wp_authenticate_username_password() handles username-and-password authentication. The hook reference documents the filter and its arguments. The wp_authenticate() reference says its identifier may be a username or email address and notes email support was added in WordPress 4.5.0.
Disable email login with a username-only rule
Add this code to a site-specific plugin or mu-plugin. It returns an authentication error when the submitted identifier is an email address; otherwise, it returns the existing result so WordPress’s regular username authentication can continue.
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<?php
/**
* Disable logging in with an email address; keep username login enabled.
*/
add_filter( 'authenticate', function ( $user, $username, $password ) {
if ( is_email( $username ) ) {
return new WP_Error(
'email_login_disabled',
__( 'Logging in with an email address is disabled. Use your username.' )
);
}
return $user;
}, 25, 3 );The hook reference documents the filter’s submitted identifier and return values: a WP_User, WP_Error, or null. WordPress registers its username and email authentication callbacks at priority 20. This example runs at priority 25, after those callbacks, and returns an error for an email identifier so it cannot complete a successful email login. See the authenticate hook reference.
Install and test the change safely
- Choose a site-specific location. Put the code in a small site-specific plugin or mu-plugin, or use a snippets manager you already trust. A site-specific plugin or mu-plugin remains separate from the active theme, so a theme change does not remove the rule.
- Keep a recovery route available. Before activating the change, stay signed in to an administrator account and confirm its username. Know how you can disable the snippet through your site’s files or deployment mechanism if login access is lost.
- Test both login cases. While the administrator session remains active, try a valid username login and confirm an email-address login is rejected with the message in the code. Also test password reset and any alternate login integrations your site uses.
- Roll back if needed. If the rule interferes with your setup or prevents access, disable the plugin, mu-plugin, or snippet using your site’s available file or deployment recovery method.
Alternative: remove the email callback
You can instead remove WordPress’s email-and-password callback and add an explicit rejection:
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remove_filter( 'authenticate', 'wp_authenticate_email_password', 20 );
add_filter( 'authenticate', function ( $user, $username ) {
if ( is_email( $username ) ) {
return new WP_Error(
'email_login_disabled',
__( 'Logging in with an email address is disabled. Use your username.' )
);
}
return $user;
}, 20, 3 );A community code example uses this remove-and-block pattern: GitHub Gist example. Prefer the first approach when you want the policy to be explicit without removing a core callback. Do not remove that callback without checking whether another authentication extension relies on it; either approach can interact with other authentication filters.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What this change does not cover
This changes the standard authenticate flow; it does not by itself define how every other authentication channel behaves. Review REST, XML-RPC, application-password, membership, and social-login integrations separately, and check their own settings or documentation if you need to restrict email-based access there. WordPress’s email-password function reference describes the email authentication callback, not the behavior of each third-party integration.
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