diff --git a/src/wp-includes/default-filters.php b/src/wp-includes/default-filters.php
index 3702c17b418e8..82e57b5441ead 100644
--- a/src/wp-includes/default-filters.php
+++ b/src/wp-includes/default-filters.php
@@ -87,17 +87,6 @@
 	add_filter( $filter, 'wp_filter_kses' );
 }
 
-// Email addresses: Allow unicode if and only if as the database can
-// store them. This affects all addresses, including those entered
-// into contact forms.
-if ( 'utf8mb4' === $wpdb->charset ) {
-	add_filter( 'is_email', 'wp_is_unicode_email', 10, 3 );
-	add_filter( 'sanitize_email', 'wp_sanitize_unicode_email', 10, 3 );
-} else {
-	add_filter( 'is_email', 'wp_is_ascii_email', 10, 3 );
-	add_filter( 'sanitize_email', 'wp_sanitize_ascii_email', 10, 3 );
-}
-
 // Display URL.
 foreach ( array( 'user_url', 'link_url', 'link_image', 'link_rss', 'comment_url', 'post_guid' ) as $filter ) {
 	if ( is_admin() ) {
@@ -282,6 +271,7 @@
 add_filter( 'the_guid', 'esc_url' );
 
 // Email filters.
+add_action( 'plugins_loaded', 'wp_select_email_address_support' );
 add_filter( 'wp_mail', 'wp_staticize_emoji_for_email' );
 
 // Robots filters.
diff --git a/src/wp-includes/class-wp-email-address.php b/src/wp-includes/email/class-wp-email-address.php
similarity index 91%
rename from src/wp-includes/class-wp-email-address.php
rename to src/wp-includes/email/class-wp-email-address.php
index fd4f0ef8937ba..09de9c74d7d0a 100644
--- a/src/wp-includes/class-wp-email-address.php
+++ b/src/wp-includes/email/class-wp-email-address.php
@@ -101,6 +101,14 @@ final class WP_Email_Address {
 	 */
 	const DOMAIN_UNICODE_REGEX = '/^' . self::DOMAIN_LABEL_UNICODE . '(?:\.' . self::DOMAIN_LABEL_UNICODE . ')*$/u';
 
+	/**
+	 * The last email address parsing error, if any.
+	 *
+	 * @since 7.1.0
+	 * @var ?string
+	 */
+	private static $last_error = null;
+
 	/**
 	 * The local part of the email address (the portion before the '@').
 	 *
@@ -198,6 +206,8 @@ private function __construct( string $localpart, string $ascii_domain, ?string $
 	 * Note! If an address contains punycode encodings but the required {@see idn_to_utf8()}
 	 * function is missing (from the `intl` extension), this will reject that email address.
 	 *
+	 * @see self::get_last_error() for why a provided address was rejected.
+	 *
 	 * @since 7.1.0
 	 *
 	 * @param string            $input         The email address string to parse.
@@ -205,9 +215,12 @@ private function __construct( string $localpart, string $ascii_domain, ?string $
 	 * @return WP_Email_Address|null A WP_Email_Address instance, or null if the input fails to validate.
 	 */
 	public static function from_string( string $input, string $character_set = 'unicode' ): ?WP_Email_Address {
+		self::$last_error = null;
+
 		// There must be exactly one '@' sign.
 		$at_pos = strpos( $input, '@' );
 		if ( false === $at_pos || strrpos( $input, '@' ) !== $at_pos ) {
+			self::$last_error = 'email_no_at';
 			return null;
 		}
 
@@ -221,6 +234,7 @@ public static function from_string( string $input, string $character_set = 'unic
 		foreach ( $domain_labels as $label ) {
 			// DNS limits each label to 63 octets.
 			if ( strlen( $label ) > 63 ) {
+				self::$last_error = 'domain_label_too_long';
 				return null;
 			}
 		}
@@ -233,6 +247,7 @@ public static function from_string( string $input, string $character_set = 'unic
 		 */
 		$needs_decoding = 1 === preg_match( '/(?:^|\.)..--/', $ascii_domain );
 		if ( $needs_decoding && ! function_exists( 'idn_to_utf8' ) ) {
+			self::$last_error = 'wp_unsupported';
 			return null;
 		}
 
@@ -247,10 +262,12 @@ public static function from_string( string $input, string $character_set = 'unic
 				if ( str_starts_with( $label, 'xn--' ) ) {
 					$label = idn_to_utf8( $label, IDNA_DEFAULT, INTL_IDNA_VARIANT_UTS46 );
 					if ( false === $label ) {
+						self::$last_error = 'domain_invalid_idn';
 						return null;
 					}
 				} elseif ( 1 === preg_match( '/^..--/', $label ) ) {
 					// Reject labels with a reserved ACE-like prefix (two chars followed by '--').
+					self::$last_error = 'domain_invalid_chars';
 					return null;
 				}
 				$decoded_labels[] = $label;
@@ -298,9 +315,24 @@ public static function from_string( string $input, string $character_set = 'unic
 
 		// Validate the domain against the allowed structure.
 		if ( 1 !== preg_match( $domain_pattern, $decoded_domain ) ) {
+			self::$last_error = 'domaind_invalid_sequence';
 			return null;
 		}
 
+		// Renormalize the ASCII domain when non-ASCII characters exist
+		if ( 1 === preg_match( '~[^\x00-\x7F]~', $ascii_domain ) ) {
+			if ( ! function_exists( 'idn_to_ascii' ) ) {
+				self::$last_error = 'wp_unsupported';
+				return null;
+			}
+
+			$labels = explode( '.', $ascii_domain );
+			foreach ( $labels as &$label ) {
+				$label = idn_to_ascii( $label, IDNA_DEFAULT, INTL_IDNA_VARIANT_UTS46 );
+			}
+			$ascii_domain = implode( '.', $labels );
+		}
+
 		return new self( $localpart, $ascii_domain, $decoded_domain );
 	}
 
@@ -402,4 +434,18 @@ public function get_ascii_address(): string {
 	public function get_unicode_address(): string {
 		return $this->localpart . '@' . $this->decoded_domain;
 	}
+
+	/**
+	 * Returns the error code for the last attempt to parse an email address,
+	 * if any error prevented recognizing the address.
+	 *
+	 * @see self::from_string()
+	 *
+	 * @since 7.1.0
+	 *
+	 * @return string|null
+	 */
+	public static function get_last_error(): ?string {
+		return self::$last_error;
+	}
 }
diff --git a/src/wp-includes/email/wp-email-support.php b/src/wp-includes/email/wp-email-support.php
new file mode 100644
index 0000000000000..7e97f59a48d3b
--- /dev/null
+++ b/src/wp-includes/email/wp-email-support.php
@@ -0,0 +1,117 @@
+<?php
+/**
+ * Email Support
+ *
+ * Governs how WordPress treats email addresses and what level of support
+ * it provides for different email addressing standards.
+ *
+ * @package WordPress
+ * @subpackage Email
+ * @since 7.1.0
+ */
+
+/**
+ * Selects which rules to apply to email addresses based on the intended
+ * level of support for Unicode, ASCII, and legacy address formats.
+ *
+ * @since 7.1.0
+ */
+function wp_select_email_address_support(): void {
+	/**
+	 * Filters the supported email address formats: Unicode, ASCII, or legacy.
+	 *
+	 * Note that Internationalized Domain Names (IDN) are supported in every
+	 * email address policy when encoded in their ASCII compatible encoding (ACE),
+	 * also known as “punycode.” Unicode email addresses makes it possible to
+	 * support addresses with non-ASCII characters in the localpart, which has
+	 * no equivalent ACE.
+	 *
+	 *  - 'unicode' supports non-US-ASCII characters in the mailbox or localpart of the address;
+	 *              e.g. "josé@españa.es" or "josé@xn--espaa-rta.es".
+	 *  - 'ascii'   applies updated parsing rules for traditional non-Unicode addresses, allowing
+	 *              for stronger interoperability with email systems.
+	 *              e.g. "jose@espana.com" or "jose@xn--espaa-rta.es".
+	 *  - 'legacy'  supports the same email addresses as before WordPress 7.1.0.
+	 *
+	 * @see https://datatracker.ietf.org/doc/html/rfc3490
+	 * @see https://datatracker.ietf.org/doc/html/rfc6530
+	 *
+	 * @since 7.1.0
+	 *
+	 * @param 'unicode'|'ascii'|'legacy' $support_level Which kinds of email addresses to allow.
+	 */
+	$support_level = apply_filters( 'wp_email_address_support', 'ascii' );
+
+	/**
+	 * If Unicode support has been requested, but the site is incapable of storing
+	 * and interacting with Unicode addresses, degrade to ASCII support.
+	 */
+	if ( 'unicode' === $support_level && ! wp_can_support_unicode_email_addresses() ) {
+		$support_level = 'ascii';
+
+		wp_trigger_error(
+			__FUNCTION__,
+			__( 'Unable to support Unicode email addresses because of missing platform support; supporting ASCII addresses instead.' ),
+			E_USER_WARNING
+		);
+	}
+
+	remove_filter( 'is_email', 'wp_is_ascii_email' );
+	remove_filter( 'is_email', 'wp_is_unicode_email' );
+	remove_filter( 'sanitize_email', 'wp_sanitize_ascii_email' );
+	remove_filter( 'sanitize_email', 'wp_sanitize_unicode_email' );
+
+	switch ( $support_level ) {
+		// Revert to pre-7.1 email address support.
+		case 'legacy':
+			break;
+
+		case 'ascii':
+			add_filter( 'is_email', 'wp_is_ascii_email', 10, 3 );
+			add_filter( 'sanitize_email', 'wp_sanitize_ascii_email', 10, 3 );
+			break;
+
+		case 'unicode':
+			add_filter( 'is_email', 'wp_is_unicode_email', 10, 3 );
+			add_filter( 'sanitize_email', 'wp_sanitize_unicode_email', 10, 3 );
+			break;
+	}
+}
+
+
+/**
+ * Returns whether Unicode email addresses could be supported.
+ *
+ * Handling Unicode email addresses depends on some platform support, namely
+ * that the emails can be stored in the database and that functionality
+ * exists to convert to and from punycode-encoded IDN domains.
+ *
+ * This function does not indicate what kind of email addresses WordPress
+ * supports, only whether it is possible to store Unicode email addresses.
+ *
+ * @see \wp_select_email_address_support() to change the support level.
+ * @see 'wp_email_address_support' filter for how to override the default support level.
+ *
+ * @since 7.1.0
+ *
+ * @return bool
+ */
+function wp_can_support_unicode_email_addresses(): bool {
+	global $wpdb;
+
+	/*
+	 * While domains can be reliably encoded with punycode and stored in ASCII,
+	 * Unicode usernames have no translation format, therefore need safe support
+	 * for storing any UTF-8 character.
+	 */
+	$is_utf8_db = 'utf8mb4' === $wpdb->charset;
+
+	/**
+	 * These functions convert into and out of punycode. Should WordPress add a polyfill
+	 * for these then this check could be removed. The {@see \WpOrg\Requests\IdnaEncoder}
+	 * class exists, but provides encoding only, and incompletely as noted in the class.
+	 */
+	$has_idn_codec = function_exists( 'idn_to_utf8' ) && function_exists( 'idn_to_ascii' );
+
+	return $is_utf8_db && $has_idn_codec;
+}
diff --git a/src/wp-includes/formatting.php b/src/wp-includes/formatting.php
index acacb131a627b..0cc694248ab20 100644
--- a/src/wp-includes/formatting.php
+++ b/src/wp-includes/formatting.php
@@ -2176,7 +2176,6 @@ function sanitize_user( $username, $strict = false ) {
 	return apply_filters( 'sanitize_user', $username, $raw_username, $strict );
 }
 
-
 /**
  * Sanitizes a string key.
  *
@@ -3600,16 +3599,12 @@ function convert_smilies( $text ) {
 }
 
 /**
- * Verifies that an email is valid.
+ * Verifies that an email is valid according to WordPress legacy rules.
  *
- * This accepts the addresses that matches the WHATWG specifications,
- * i.e. what browsers use for `<input type=email>`. It also accepts some
- * additional addresses.
+ * Does not grok i18n domains. Not RFC compliant.
  *
- * By default this accepts addresses like info@grå.org (also accepted
- * by Firefox) `<input type=email>`. You can disable Unicode support by
- * using the wp_is_ascii_email filter instead of wp_is_unicode_email,
- * which is the default.
+ * @see wp_is_ascii_email()
+ * @see wp_is_unicode_email()
  *
  * @since 0.71
  *
@@ -3622,21 +3617,84 @@ function is_email( $email, $deprecated = false ) {
 		_deprecated_argument( __FUNCTION__, '3.0.0' );
 	}
 
-	/**
-	 * Filters whether an email address is valid.
-	 *
-	 * This filter is evaluated under several different contexts, such as
-	 * 'local_invalid_chars', 'domain_no_periods', or no specific context.
-	 * Filters registered on this hook perform the actual validation; the
-	 * default filter is registered in default-filters.php.
-	 *
-	 * @since 2.8.0
-	 *
-	 * @param string|false $is_email The email address if successfully passed the is_email() checks, false otherwise.
-	 * @param string       $email    The email address being checked.
-	 * @param string|null  $context  Context under which the email was tested, or null for the initial call.
+	// Test for the minimum length the email can be.
+	if ( strlen( $email ) < 6 ) {
+		/**
+		 * Filters whether an email address is valid.
+		 *
+		 * This filter is evaluated under several different contexts, such as 'email_too_short',
+		 * 'email_no_at', 'local_invalid_chars', 'domain_period_sequence', 'domain_period_limits',
+		 * 'domain_no_periods', 'sub_hyphen_limits', 'sub_invalid_chars', or no specific context.
+		 *
+		 * @since 2.8.0
+		 *
+		 * @param string|false $is_email The email address if successfully passed the is_email() checks, false otherwise.
+		 * @param string       $email    The email address being checked.
+		 * @param string       $context  Context under which the email was tested.
+		 */
+		return apply_filters( 'is_email', false, $email, 'email_too_short' );
+	}
+
+	// Test for an @ character after the first position.
+	if ( false === strpos( $email, '@', 1 ) ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'is_email', false, $email, 'email_no_at' );
+	}
+
+	// Split out the local and domain parts.
+	list( $local, $domain ) = explode( '@', $email, 2 );
+
+	/*
+	 * LOCAL PART
+	 * Test for invalid characters.
+	 */
+	if ( ! preg_match( '/^[a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.-]+$/', $local ) ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'is_email', false, $email, 'local_invalid_chars' );
+	}
+
+	/*
+	 * DOMAIN PART
+	 * Test for sequences of periods.
 	 */
-	return apply_filters( 'is_email', false, $email, null );
+	if ( preg_match( '/\.{2,}/', $domain ) ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'is_email', false, $email, 'domain_period_sequence' );
+	}
+
+	// Test for leading and trailing periods and whitespace.
+	if ( trim( $domain, " \t\n\r\0\x0B." ) !== $domain ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'is_email', false, $email, 'domain_period_limits' );
+	}
+
+	// Split the domain into subs.
+	$subs = explode( '.', $domain );
+
+	// Assume the domain will have at least two subs.
+	if ( 2 > count( $subs ) ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'is_email', false, $email, 'domain_no_periods' );
+	}
+
+	// Loop through each sub.
+	foreach ( $subs as $sub ) {
+		// Test for leading and trailing hyphens and whitespace.
+		if ( trim( $sub, " \t\n\r\0\x0B-" ) !== $sub ) {
+			/** This filter is documented in wp-includes/formatting.php */
+			return apply_filters( 'is_email', false, $email, 'sub_hyphen_limits' );
+		}
+
+		// Test for invalid characters.
+		if ( ! preg_match( '/^[a-z0-9-]+$/i', $sub ) ) {
+			/** This filter is documented in wp-includes/formatting.php */
+			return apply_filters( 'is_email', false, $email, 'sub_invalid_chars' );
+		}
+	}
+
+	// Congratulations, your email made it!
+	/** This filter is documented in wp-includes/formatting.php */
+	return apply_filters( 'is_email', $email, $email, null );
 }
 
 /**
@@ -3809,60 +3867,109 @@ function iso8601_to_datetime( $date_string, $timezone = 'user' ) {
 }
 
 /**
- * Sanitizes an email address.
- *
- * Strips stray whitespace from the input, then strips trailing dots from the domain.
- * This is designed to recover from cut/paste mistakes without any risk of transforming
- * the input into a different address than the user intended.
- *
- * Validation and final form are determined by the 'sanitize_email' filter; the default
- * filter is registered in default-filters.php and delegates to {@see WP_Email_Address::from_string()}.
+ * Strips out all characters that are not allowable in an email.
  *
  * @since 1.5.0
- * @since 7.1.0 Accepts Unicode email addresses on supporting platforms.
  *
- * @param string $email Email address to sanitize.
- * @return string The sanitized email address, or an empty string if invalid.
+ * @param string $email Email address to filter.
+ * @return string Filtered email address.
  */
 function sanitize_email( $email ) {
-	// Strip surrounding whitespace.
-	$email = trim( $email );
+	// Test for the minimum length the email can be.
+	if ( strlen( $email ) < 6 ) {
+		/**
+		 * Filters a sanitized email address.
+		 *
+		 * This filter is evaluated under several contexts, including 'email_too_short',
+		 * 'email_no_at', 'local_invalid_chars', 'domain_period_sequence', 'domain_period_limits',
+		 * 'domain_no_periods', 'domain_no_valid_subs', or no context.
+		 *
+		 * @since 2.8.0
+		 *
+		 * @param string $sanitized_email The sanitized email address.
+		 * @param string $email           The email address, as provided to sanitize_email().
+		 * @param string|null $message    A message to pass to the user. null if email is sanitized.
+		 */
+		return apply_filters( 'sanitize_email', '', $email, 'email_too_short' );
+	}
 
-	// Extract the address from "Display Name <username@domain>" format.
-	if ( 1 === preg_match( '/<([^>]+)>$/', $email, $matches ) ) {
-		$email = $matches[1];
+	// Test for an @ character after the first position.
+	if ( false === strpos( $email, '@', 1 ) ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'sanitize_email', '', $email, 'email_no_at' );
 	}
 
+	// Split out the local and domain parts.
+	list( $local, $domain ) = explode( '@', $email, 2 );
+
 	/*
-	 * Strip soft hyphens and whitespace adjacent to structural separators (dots and @),
-	 * e.g. copy-paste artifacts like "info@example\u{00AD}.com" or "info@example .com".
-	 *
-	 * In some cases, e.g. autocorrect, some older software has been seen to add the
-	 * space for unrecognized TLDs. This re-joins the parts for proper examination.
+	 * LOCAL PART
+	 * Test for invalid characters.
 	 */
-	$email = preg_replace( '/[\x{00AD}\s]*([.@])[\x{00AD}\s]*/u', '$1', $email ) ?? $email;
-
-	// Strip a trailing dot from the domain (e.g. if pasted from the end of a sentence).
-	if ( str_contains( $email, '@' ) ) {
-		list( $local, $domain ) = explode( '@', $email, 2 );
-		$domain                 = rtrim( $domain, '.' );
-		$email                  = $local . '@' . $domain;
+	$local = preg_replace( '/[^a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.-]/', '', $local );
+	if ( '' === $local ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'sanitize_email', '', $email, 'local_invalid_chars' );
 	}
 
-	/**
-	 * Filters a sanitized email address.
-	 *
-	 * Filters registered on this hook perform the actual validation and return
-	 * the canonical email string on success or an empty string on failure.
-	 * The default filter is registered in default-filters.php.
-	 *
-	 * @since 2.8.0
-	 *
-	 * @param string      $sanitized_email The sanitized email address, or empty string.
-	 * @param string      $email           The email address as provided to sanitize_email().
-	 * @param string|null $context         Validation context, or null for the initial call.
+	/*
+	 * DOMAIN PART
+	 * Test for sequences of periods.
 	 */
-	return apply_filters( 'sanitize_email', '', $email, null );
+	$domain = preg_replace( '/\.{2,}/', '', $domain );
+	if ( '' === $domain ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'sanitize_email', '', $email, 'domain_period_sequence' );
+	}
+
+	// Test for leading and trailing periods and whitespace.
+	$domain = trim( $domain, " \t\n\r\0\x0B." );
+	if ( '' === $domain ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'sanitize_email', '', $email, 'domain_period_limits' );
+	}
+
+	// Split the domain into subs.
+	$subs = explode( '.', $domain );
+
+	// Assume the domain will have at least two subs.
+	if ( 2 > count( $subs ) ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'sanitize_email', '', $email, 'domain_no_periods' );
+	}
+
+	// Create an array that will contain valid subs.
+	$new_subs = array();
+
+	// Loop through each sub.
+	foreach ( $subs as $sub ) {
+		// Test for leading and trailing hyphens.
+		$sub = trim( $sub, " \t\n\r\0\x0B-" );
+
+		// Test for invalid characters.
+		$sub = preg_replace( '/[^a-z0-9-]+/i', '', $sub );
+
+		// If there's anything left, add it to the valid subs.
+		if ( '' !== $sub ) {
+			$new_subs[] = $sub;
+		}
+	}
+
+	// If there aren't 2 or more valid subs.
+	if ( 2 > count( $new_subs ) ) {
+		/** This filter is documented in wp-includes/formatting.php */
+		return apply_filters( 'sanitize_email', '', $email, 'domain_no_valid_subs' );
+	}
+
+	// Join valid subs into the new domain.
+	$domain = implode( '.', $new_subs );
+
+	// Put the email back together.
+	$sanitized_email = $local . '@' . $domain;
+
+	// Congratulations, your email made it!
+	/** This filter is documented in wp-includes/formatting.php */
+	return apply_filters( 'sanitize_email', $sanitized_email, $email, null );
 }
 
 /**
diff --git a/src/wp-settings.php b/src/wp-settings.php
index dc01c516ca810..48af51a4ec5dc 100644
--- a/src/wp-settings.php
+++ b/src/wp-settings.php
@@ -112,7 +112,7 @@
 require ABSPATH . WPINC . '/class-wp-list-util.php';
 require ABSPATH . WPINC . '/class-wp-token-map.php';
 require ABSPATH . WPINC . '/utf8.php';
-require ABSPATH . WPINC . '/class-wp-email-address.php';
+require ABSPATH . WPINC . '/email/class-wp-email-address.php';
 require ABSPATH . WPINC . '/formatting.php';
 require ABSPATH . WPINC . '/meta.php';
 require ABSPATH . WPINC . '/functions.php';