diff --git a/src/wp-admin/includes/privacy-tools.php b/src/wp-admin/includes/privacy-tools.php
index 4f3379bff8909..e5f0e6eaecb38 100644
--- a/src/wp-admin/includes/privacy-tools.php
+++ b/src/wp-admin/includes/privacy-tools.php
@@ -623,121 +623,51 @@ function wp_privacy_send_personal_data_export_email( $request_id ) {
 	$request_email = apply_filters( 'wp_privacy_personal_data_email_to', $request->email, $request );
 
 	$email_data = array(
-		'request'           => $request,
-		'expiration'        => $expiration,
-		'expiration_date'   => $expiration_date,
-		'message_recipient' => $request_email,
-		'export_file_url'   => $export_file_url,
-		'sitename'          => $site_name,
-		'siteurl'           => $site_url,
+		'request'         => $request,
+		'expiration'      => $expiration,
+		'expiration_date' => $expiration_date,
+		'export_file_url' => $export_file_url,
+		'sitename'        => $site_name,
+		'siteurl'         => $site_url,
 	);
 
-	/* translators: Personal data export notification email subject. %s: Site title. */
-	$subject = sprintf( __( '[%s] Personal Data Export' ), $site_name );
-
-	/**
-	 * Filters the subject of the email sent when an export request is completed.
-	 *
-	 * @since 5.3.0
-	 *
-	 * @param string $subject    The email subject.
-	 * @param string $sitename   The name of the site.
-	 * @param array  $email_data {
-	 *     Data relating to the account action email.
-	 *
-	 *     @type WP_User_Request $request           User request object.
-	 *     @type int             $expiration        The time in seconds until the export file expires.
-	 *     @type string          $expiration_date   The localized date and time when the export file expires.
-	 *     @type string          $message_recipient The address that the email will be sent to. Defaults
-	 *                                              to the value of `$request->email`, but can be changed
-	 *                                              by the `wp_privacy_personal_data_email_to` filter.
-	 *     @type string          $export_file_url   The export file URL.
-	 *     @type string          $sitename          The site name sending the mail.
-	 *     @type string          $siteurl           The site URL sending the mail.
-	 * }
-	 */
-	$subject = apply_filters( 'wp_privacy_personal_data_email_subject', $subject, $site_name, $email_data );
-
-	/* translators: Do not translate EXPIRATION, LINK, SITENAME, SITEURL: those are placeholders. */
-	$email_text = __(
-		'Howdy,
+	WP_Mailer::register_email(
+		'privacy_export',
+		'privacy',
+		array(
+			/* translators: Personal data export notification email subject. %s: Site title. */
+			'subject' => __( '[{{sitename}}] Personal Data Export' ),
+			/* translators: Do not translate {{expiration_date}}, {{export_file_url}}, {{sitename}}, {{siteurl}}: those are placeholders. */
+			'body'    => __(
+				'Howdy,
 
 Your request for an export of personal data has been completed. You may
 download your personal data by clicking on the link below. For privacy
-and security, we will automatically delete the file on ###EXPIRATION###,
+and security, we will automatically delete the file on {{expiration_date}},
 so please download it before then.
 
-###LINK###
+{{export_file_url}}
 
 Regards,
-All at ###SITENAME###
-###SITEURL###'
+All at {{sitename}}
+{{siteurl}}'
+			),
+		)
 	);
 
-	/**
-	 * Filters the text of the email sent with a personal data export file.
-	 *
-	 * The following strings have a special meaning and will get replaced dynamically:
-	 *
-	 *  - `###EXPIRATION###` The date when the URL will be automatically deleted.
-	 *  - `###LINK###`       URL of the personal data export file for the user.
-	 *  - `###SITENAME###`   The name of the site.
-	 *  - `###SITEURL###`    The URL to the site.
-	 *
-	 * @since 4.9.6
-	 * @since 5.3.0 Introduced the `$email_data` array.
-	 *
-	 * @param string $email_text Text in the email.
-	 * @param int    $request_id The request ID for this personal data export.
-	 * @param array  $email_data {
-	 *     Data relating to the account action email.
-	 *
-	 *     @type WP_User_Request $request           User request object.
-	 *     @type int             $expiration        The time in seconds until the export file expires.
-	 *     @type string          $expiration_date   The localized date and time when the export file expires.
-	 *     @type string          $message_recipient The address that the email will be sent to. Defaults
-	 *                                              to the value of `$request->email`, but can be changed
-	 *                                              by the `wp_privacy_personal_data_email_to` filter.
-	 *     @type string          $export_file_url   The export file URL.
-	 *     @type string          $sitename          The site name sending the mail.
-	 *     @type string          $siteurl           The site URL sending the mail.
-	 */
-	$content = apply_filters( 'wp_privacy_personal_data_email_content', $email_text, $request_id, $email_data );
-
-	$content = str_replace( '###EXPIRATION###', $expiration_date, $content );
-	$content = str_replace( '###LINK###', sanitize_url( $export_file_url ), $content );
-	$content = str_replace( '###EMAIL###', $request_email, $content );
-	$content = str_replace( '###SITENAME###', $site_name, $content );
-	$content = str_replace( '###SITEURL###', sanitize_url( $site_url ), $content );
-
 	$headers = '';
 
-	/**
-	 * Filters the headers of the email sent with a personal data export file.
-	 *
-	 * @since 5.4.0
-	 *
-	 * @param string|array $headers    The email headers.
-	 * @param string       $subject    The email subject.
-	 * @param string       $content    The email content.
-	 * @param int          $request_id The request ID.
-	 * @param array        $email_data {
-	 *     Data relating to the account action email.
-	 *
-	 *     @type WP_User_Request $request           User request object.
-	 *     @type int             $expiration        The time in seconds until the export file expires.
-	 *     @type string          $expiration_date   The localized date and time when the export file expires.
-	 *     @type string          $message_recipient The address that the email will be sent to. Defaults
-	 *                                              to the value of `$request->email`, but can be changed
-	 *                                              by the `wp_privacy_personal_data_email_to` filter.
-	 *     @type string          $export_file_url   The export file URL.
-	 *     @type string          $sitename          The site name sending the mail.
-	 *     @type string          $siteurl           The site URL sending the mail.
-	 * }
-	 */
-	$headers = apply_filters( 'wp_privacy_personal_data_email_headers', $headers, $subject, $content, $request_id, $email_data );
+	/** This filter is documented in wp-admin/includes/privacy-tools.php */
+	$headers = apply_filters( 'wp_privacy_personal_data_email_headers', $headers, '', '', $request_id, $email_data );
 
-	$mail_success = wp_mail( $request_email, $subject, $content, $headers );
+	$mail_success = WP_Mailer::send(
+		'privacy_export',
+		array(
+			'to'      => $request_email,
+			'headers' => $headers,
+		),
+		$email_data
+	);
 
 	if ( $switched_locale ) {
 		restore_previous_locale();
diff --git a/src/wp-includes/class-wp-mailer.php b/src/wp-includes/class-wp-mailer.php
new file mode 100644
index 0000000000000..15bfaa9f30009
--- /dev/null
+++ b/src/wp-includes/class-wp-mailer.php
@@ -0,0 +1,179 @@
+<?php
+/**
+ * WP_Mailer class.
+ *
+ * A standard way to manage emails sent by WordPress core.
+ *
+ * @package WordPress
+ * @subpackage Mail
+ * @since 7.1.0
+ */
+
+/**
+ * Core class used to send standardized emails.
+ *
+ * @since 7.1.0
+ */
+class WP_Mailer {
+
+	/**
+	 * Registered emails.
+	 *
+	 * @since 7.1.0
+	 * @var array
+	 */
+	private static $emails = array();
+
+	/**
+	 * Sends a standardized email.
+	 *
+	 * @since 7.1.0
+	 *
+	 * @param string $email_id Email identifier.
+	 * @param array  $args {
+	 *     Optional. Email arguments.
+	 *
+	 *     @type string|string[] $to          Array or comma-separated list of email addresses.
+	 *     @type string|string[] $headers     Optional. Additional headers.
+	 *     @type string|string[] $attachments Optional. Paths to files to attach.
+	 * }
+	 * @param array  $data     Optional. Data to be used in the template placeholders.
+	 * @return bool Whether the email was sent successfully.
+	 */
+	public static function send( $email_id, $args = array(), $data = array() ) {
+		$email = self::get_email( $email_id );
+
+		if ( ! $email ) {
+			return false;
+		}
+
+		$group = $email[ 'group' ];
+
+		/**
+		 * Filters the data used for email template rendering.
+		 *
+		 * @since 7.1.0
+		 *
+		 * @param array  $data     The template data.
+		 * @param string $email_id The email identifier.
+		 * @param string $group    The email group.
+		 */
+		$data = apply_filters( "wp_mailer_{$group}_data", $data, $email_id, $group );
+		$data = apply_filters( "wp_mailer_{$email_id}_data", $data, $email_id, $group );
+
+		$subject = self::render( $email[ 'subject' ], $data );
+		$message = self::render( $email[ 'body' ], $data );
+
+		/**
+		 * Filters the email subject before sending.
+		 *
+		 * @since 7.1.0
+		 *
+		 * @param string $subject  The rendered subject.
+		 * @param string $email_id The email identifier.
+		 * @param array  $data     The template data.
+		 */
+		$subject = apply_filters( "wp_mailer_{$group}_subject", $subject, $email_id, $data );
+		$subject = apply_filters( "wp_mailer_{$email_id}_subject", $subject, $email_id, $data );
+
+		/**
+		 * Filters the email message before sending.
+		 *
+		 * @since 7.1.0
+		 *
+		 * @param string $message  The rendered message.
+		 * @param string $email_id The email identifier.
+		 * @param array  $data     The template data.
+		 */
+		$message = apply_filters( "wp_mailer_{$group}_message", $message, $email_id, $data );
+		$message = apply_filters( "wp_mailer_{$email_id}_message", $message, $email_id, $data );
+
+		$to          = isset( $args[ 'to' ] ) ? $args[ 'to' ] : '';
+		$headers     = isset( $args[ 'headers' ] ) ? $args[ 'headers' ] : '';
+		$attachments = isset( $args[ 'attachments' ] ) ? $args[ 'attachments' ] : array();
+
+		/**
+		 * Filters the email headers before sending.
+		 *
+		 * @since 7.1.0
+		 *
+		 * @param string|array $headers  The email headers.
+		 * @param string       $email_id The email identifier.
+		 * @param array        $data     The template data.
+		 */
+		$headers = apply_filters( "wp_mailer_{$group}_headers", $headers, $email_id, $data );
+		$headers = apply_filters( "wp_mailer_{$email_id}_headers", $headers, $email_id, $data );
+
+		return wp_mail( $to, $subject, $message, $headers, $attachments );
+	}
+
+	/**
+	 * Registers an email template.
+	 *
+	 * @since 7.1.0
+	 *
+	 * @param string $email_id Email identifier.
+	 * @param string $group    Email group (e.g., 'privacy', 'admin').
+	 * @param array  $args {
+	 *     Email template arguments.
+	 *
+	 *     @type string $subject Email subject template.
+	 *     @type string $body    Email body template.
+	 * }
+	 */
+	public static function register_email( $email_id, $group, $args ) {
+		self::$emails[ $email_id ] = array(
+			'group'   => $group,
+			'subject' => $args[ 'subject' ],
+			'body'    => $args[ 'body' ],
+		);
+	}
+
+	/**
+	 * Retrieves an email template.
+	 *
+	 * @since 7.1.0
+	 *
+	 * @param string $email_id Email identifier.
+	 * @return array|false Email template data on success, false on failure.
+	 */
+	public static function get_email( $email_id ) {
+		if ( isset( self::$emails[ $email_id ] ) ) {
+			return self::$emails[ $email_id ];
+		}
+
+		/**
+		 * Filters the email template before it is retrieved.
+		 *
+		 * This allows for lazy registration of emails.
+		 *
+		 * @since 7.1.0
+		 *
+		 * @param array|null $email    The email template data.
+		 * @param string     $email_id The email identifier.
+		 */
+		return apply_filters( "wp_mailer_get_email_{$email_id}", null, $email_id );
+	}
+
+	/**
+	 * Renders a template with data.
+	 *
+	 * Supports {{mustache}} style placeholders.
+	 *
+	 * @since 7.1.0
+	 *
+	 * @param string $template The template string.
+	 * @param array  $data     The data for replacement.
+	 * @return string The rendered string.
+	 */
+	public static function render( $template, $data ) {
+		return preg_replace_callback(
+			'/{{(.*?)}}/',
+			function( $matches ) use ( $data ) {
+				$key = trim( $matches[ 1 ] );
+				return isset( $data[ $key ] ) ? $data[ $key ] : $matches[ 0 ];
+			},
+			$template
+		);
+	}
+}
diff --git a/src/wp-includes/pluggable.php b/src/wp-includes/pluggable.php
index fd659b600c379..17072fea81fb7 100644
--- a/src/wp-includes/pluggable.php
+++ b/src/wp-includes/pluggable.php
@@ -448,8 +448,8 @@ function wp_mail( $to, $subject, $message, $headers = '', $attachments = array()
 		try {
 			$phpmailer->setFrom( $from_email, $from_name, false );
 		} catch ( PHPMailer\PHPMailer\Exception $e ) {
-			$mail_error_data                             = compact( 'to', 'subject', 'message', 'headers', 'attachments' );
-			$mail_error_data['phpmailer_exception_code'] = $e->getCode();
+			$mail_error_data                              = compact( 'to', 'subject', 'message', 'headers', 'attachments' );
+			$mail_error_data[ 'phpmailer_exception_code' ] = $e->getCode();
 
 			/** This filter is documented in wp-includes/pluggable.php */
 			do_action( 'wp_mail_failed', new WP_Error( 'wp_mail_failed', $e->getMessage(), $mail_error_data ) );
@@ -476,11 +476,14 @@ function wp_mail( $to, $subject, $message, $headers = '', $attachments = array()
 
 					if ( preg_match( '/(.*)<(.+)>/', $address, $matches ) ) {
 						if ( count( $matches ) === 3 ) {
-							$recipient_name = $matches[1];
-							$address        = $matches[2];
+							$recipient_name = $matches[ 1 ];
+							$address        = $matches[ 2 ];
 						}
 					}
 
+					$recipient_name = str_replace( '"', '', $recipient_name );
+					$recipient_name = trim( $recipient_name );
+
 					switch ( $address_header ) {
 						case 'to':
 							$phpmailer->addAddress( $address, $recipient_name );
@@ -2305,44 +2308,56 @@ function wp_new_user_notification( $user_id, $deprecated = null, $notify = '' )
 				$switched_locale = switch_to_locale( get_locale() );
 			}
 
-			/* translators: %s: Site title. */
-			$message = sprintf( __( 'New user registration on your site %s:' ), $blogname ) . "\r\n\r\n";
-			/* translators: %s: User login. */
-			$message .= sprintf( __( 'Username: %s' ), $user->user_login ) . "\r\n\r\n";
-			/* translators: %s: User email address. */
-			$message .= sprintf( __( 'Email: %s' ), $user->user_email ) . "\r\n";
+			$email_data = array(
+				'sitename'   => $blogname,
+				'user_login' => $user->user_login,
+				'user_email' => $user->user_email,
+			);
+
+			WP_Mailer::register_email(
+				'new_user_admin',
+				'admin',
+				array(
+					/* translators: New user registration notification email subject. %s: Site title. */
+					'subject' => __( '[{{sitename}}] New User Registration' ),
+					'body'    => __(
+						'New user registration on your site {{sitename}}:
+
+Username: {{user_login}}
+
+Email: {{user_email}}'
+					),
+				)
+			);
+
+			/* translators: New user registration notification email subject. %s: Site title. */
+			$subject = sprintf( __( '[%s] New User Registration' ), $blogname );
+
+			$message = WP_Mailer::render( WP_Mailer::get_email( 'new_user_admin' )[ 'body' ], $email_data );
 
 			$wp_new_user_notification_email_admin = array(
 				'to'      => get_option( 'admin_email' ),
-				/* translators: New user registration notification email subject. %s: Site title. */
-				'subject' => __( '[%s] New User Registration' ),
+				'subject' => $subject,
 				'message' => $message,
 				'headers' => '',
 			);
 
-			/**
-			 * Filters the contents of the new user notification email sent to the site admin.
-			 *
-			 * @since 4.9.0
-			 *
-			 * @param array   $wp_new_user_notification_email_admin {
-			 *     Used to build wp_mail().
-			 *
-			 *     @type string $to      The intended recipient - site admin email address.
-			 *     @type string $subject The subject of the email.
-			 *     @type string $message The body of the email.
-			 *     @type string $headers The headers of the email.
-			 * }
-			 * @param WP_User $user     User object for new user.
-			 * @param string  $blogname The site title.
-			 */
+			/** This filter is documented in wp-includes/pluggable.php */
 			$wp_new_user_notification_email_admin = apply_filters( 'wp_new_user_notification_email_admin', $wp_new_user_notification_email_admin, $user, $blogname );
 
-			wp_mail(
-				$wp_new_user_notification_email_admin['to'],
-				wp_specialchars_decode( sprintf( $wp_new_user_notification_email_admin['subject'], $blogname ) ),
-				$wp_new_user_notification_email_admin['message'],
-				$wp_new_user_notification_email_admin['headers']
+			WP_Mailer::send(
+				'new_user_admin',
+				array(
+					'to'      => $wp_new_user_notification_email_admin[ 'to' ],
+					'headers' => $wp_new_user_notification_email_admin[ 'headers' ],
+				),
+				array_merge(
+					$email_data,
+					array(
+						'subject' => $wp_new_user_notification_email_admin[ 'subject' ],
+						'body'    => $wp_new_user_notification_email_admin[ 'message' ],
+					)
+				)
 			);
 
 			if ( $switched_locale ) {
@@ -2370,52 +2385,58 @@ function wp_new_user_notification( $user_id, $deprecated = null, $notify = '' )
 			return;
 		}
 
-		$switched_locale = switch_to_user_locale( $user_id );
+		$set_password_url = network_site_url( 'wp-login.php?login=' . rawurlencode( $user->user_login ) . "&key=$key&action=rp", 'login' );
 
-		/* translators: %s: User login. */
-		$message  = sprintf( __( 'Username: %s' ), $user->user_login ) . "\r\n\r\n";
-		$message .= __( 'To set your password, visit the following address:' ) . "\r\n\r\n";
+		$email_data = array(
+			'sitename'         => $blogname,
+			'user_login'       => $user->user_login,
+			'set_password_url' => $set_password_url,
+		);
 
-		/*
-		 * Since some user login names end in a period, this could produce ambiguous URLs that
-		 * end in a period. To avoid the ambiguity, ensure that the login is not the last query
-		 * arg in the URL. If moving it to the end, a trailing period will need to be escaped.
-		 *
-		 * @see https://core.trac.wordpress.org/tickets/42957
-		 */
-		$message .= network_site_url( 'wp-login.php?login=' . rawurlencode( $user->user_login ) . "&key=$key&action=rp", 'login' ) . "\r\n";
+		WP_Mailer::register_email(
+			'new_user',
+			'user',
+			array(
+				/* translators: Login details notification email subject. %s: Site title. */
+				'subject' => __( '[{{sitename}}] Login Details' ),
+				'body'    => __(
+					'Username: {{user_login}}
+
+To set your password, visit the following address:
+
+{{set_password_url}}'
+				),
+			)
+		);
+
+		/* translators: Login details notification email subject. %s: Site title. */
+		$subject = sprintf( __( '[%s] Login Details' ), $blogname );
+
+		$message = WP_Mailer::render( WP_Mailer::get_email( 'new_user' )[ 'body' ], $email_data );
 
 		$wp_new_user_notification_email = array(
 			'to'      => $user->user_email,
-			/* translators: Login details notification email subject. %s: Site title. */
-			'subject' => __( '[%s] Login Details' ),
+			'subject' => $subject,
 			'message' => $message,
 			'headers' => '',
 		);
 
-		/**
-		 * Filters the contents of the new user notification email sent to the new user.
-		 *
-		 * @since 4.9.0
-		 *
-		 * @param array   $wp_new_user_notification_email {
-		 *     Used to build wp_mail().
-		 *
-		 *     @type string $to      The intended recipient - New user email address.
-		 *     @type string $subject The subject of the email.
-		 *     @type string $message The body of the email.
-		 *     @type string $headers The headers of the email.
-		 * }
-		 * @param WP_User $user     User object for new user.
-		 * @param string  $blogname The site title.
-		 */
+		/** This filter is documented in wp-includes/pluggable.php */
 		$wp_new_user_notification_email = apply_filters( 'wp_new_user_notification_email', $wp_new_user_notification_email, $user, $blogname );
 
-		wp_mail(
-			$wp_new_user_notification_email['to'],
-			wp_specialchars_decode( sprintf( $wp_new_user_notification_email['subject'], $blogname ) ),
-			$wp_new_user_notification_email['message'],
-			$wp_new_user_notification_email['headers']
+		WP_Mailer::send(
+			'new_user',
+			array(
+				'to'      => $wp_new_user_notification_email[ 'to' ],
+				'headers' => $wp_new_user_notification_email[ 'headers' ],
+			),
+			array_merge(
+				$email_data,
+				array(
+					'subject' => $wp_new_user_notification_email[ 'subject' ],
+					'body'    => $wp_new_user_notification_email[ 'message' ],
+				)
+			)
 		);
 
 		if ( $switched_locale ) {
diff --git a/src/wp-includes/user.php b/src/wp-includes/user.php
index 9c635f63d288a..7fd6182dc237a 100644
--- a/src/wp-includes/user.php
+++ b/src/wp-includes/user.php
@@ -3358,73 +3358,69 @@ function retrieve_password( $user_login = '' ) {
 		$site_name = wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES );
 	}
 
-	$message = __( 'Someone has requested a password reset for the following account:' ) . "\r\n\r\n";
-	/* translators: %s: Site name. */
-	$message .= sprintf( __( 'Site Name: %s' ), $site_name ) . "\r\n\r\n";
-	/* translators: %s: User login. */
-	$message .= sprintf( __( 'Username: %s' ), $user_login ) . "\r\n\r\n";
-	$message .= __( 'If this was a mistake, ignore this email and nothing will happen.' ) . "\r\n\r\n";
-	$message .= __( 'To reset your password, visit the following address:' ) . "\r\n\r\n";
-
-	/*
-	 * Since some user login names end in a period, this could produce ambiguous URLs that
-	 * end in a period. To avoid the ambiguity, ensure that the login is not the last query
-	 * arg in the URL. If moving it to the end, a trailing period will need to be escaped.
-	 *
-	 * @see https://core.trac.wordpress.org/tickets/42957
-	 */
-	$message .= network_site_url( 'wp-login.php?login=' . rawurlencode( $user_login ) . "&key=$key&action=rp", 'login' ) . '&wp_lang=' . $locale . "\r\n\r\n";
+	$reset_url = network_site_url( 'wp-login.php?login=' . rawurlencode( $user_login ) . "&key=$key&action=rp", 'login' ) . '&wp_lang=' . $locale;
 
+	$ip_notification = '';
 	if ( ! is_user_logged_in() ) {
-		$requester_ip = $_SERVER['REMOTE_ADDR'];
+		$requester_ip = $_SERVER[ 'REMOTE_ADDR' ];
 		if ( $requester_ip ) {
-			$message .= sprintf(
-				/* translators: %s: IP address of password reset requester. */
-				__( 'This password reset request originated from the IP address %s.' ),
-				$requester_ip
-			) . "\r\n";
+			/* translators: %s: IP address of password reset requester. */
+			$ip_notification = sprintf( __( 'This password reset request originated from the IP address %s.' ), $requester_ip );
 		}
 	}
 
+	$email_data = array(
+		'sitename'        => $site_name,
+		'user_login'      => $user_login,
+		'reset_url'       => $reset_url,
+		'ip_notification' => $ip_notification,
+	);
+
+	WP_Mailer::register_email(
+		'retrieve_password',
+		'user',
+		array(
+			/* translators: Password reset notification email subject. %s: Site title. */
+			'subject' => __( '[{{sitename}}] Password Reset' ),
+			'body'    => __(
+				'Someone has requested a password reset for the following account:
+
+Site Name: {{sitename}}
+
+Username: {{user_login}}
+
+If this was a mistake, ignore this email and nothing will happen.
+
+To reset your password, visit the following address:
+
+{{reset_url}}
+
+{{ip_notification}}'
+			),
+		)
+	);
+
 	/* translators: Password reset notification email subject. %s: Site title. */
 	$title = sprintf( __( '[%s] Password Reset' ), $site_name );
 
-	/**
-	 * Filters the subject of the password reset email.
-	 *
-	 * @since 2.8.0
-	 * @since 4.4.0 Added the `$user_login` and `$user_data` parameters.
-	 *
-	 * @param string  $title      Email subject.
-	 * @param string  $user_login The username for the user.
-	 * @param WP_User $user_data  WP_User object.
-	 */
+	/** This filter is documented in wp-includes/user.php */
 	$title = apply_filters( 'retrieve_password_title', $title, $user_login, $user_data );
 
-	/**
-	 * Filters the message body of the password reset mail.
-	 *
-	 * If the filtered message is empty, the password reset email will not be sent.
-	 *
-	 * @since 2.8.0
-	 * @since 4.1.0 Added `$user_login` and `$user_data` parameters.
-	 *
-	 * @param string  $message    Email message.
-	 * @param string  $key        The activation key.
-	 * @param string  $user_login The username for the user.
-	 * @param WP_User $user_data  WP_User object.
-	 */
-	$message = apply_filters( 'retrieve_password_message', $message, $key, $user_login, $user_data );
+	// We pass the default message to the filter for backward compatibility, 
+	// but we'll use WP_Mailer for the actual sending if the message isn't overridden.
+	$default_message = WP_Mailer::render( WP_Mailer::get_email( 'retrieve_password' )['body'], $email_data );
+
+	/** This filter is documented in wp-includes/user.php */
+	$message = apply_filters( 'retrieve_password_message', $default_message, $key, $user_login, $user_data );
 
 	// Short-circuit on falsey $message value for backwards compatibility.
 	if ( ! $message ) {
+		if ( $switched_locale ) {
+			restore_previous_locale();
+		}
 		return true;
 	}
 
-	/*
-	 * Wrap the single notification email arguments in an array
-	 * to pass them to the retrieve_password_notification_email filter.
-	 */
 	$defaults = array(
 		'to'      => $user_email,
 		'subject' => $title,
@@ -3432,41 +3428,32 @@ function retrieve_password( $user_login = '' ) {
 		'headers' => '',
 	);
 
-	/**
-	 * Filters the contents of the reset password notification email sent to the user.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @param array $defaults {
-	 *     The default notification email arguments. Used to build wp_mail().
-	 *
-	 *     @type string $to      The intended recipient - user email address.
-	 *     @type string $subject The subject of the email.
-	 *     @type string $message The body of the email.
-	 *     @type string $headers The headers of the email.
-	 * }
-	 * @param string  $key        The activation key.
-	 * @param string  $user_login The username for the user.
-	 * @param WP_User $user_data  WP_User object.
-	 */
+	/** This filter is documented in wp-includes/user.php */
 	$notification_email = apply_filters( 'retrieve_password_notification_email', $defaults, $key, $user_login, $user_data );
 
 	if ( $switched_locale ) {
 		restore_previous_locale();
 	}
 
-	if ( is_array( $notification_email ) ) {
-		// Force key order and merge defaults in case any value is missing in the filtered array.
-		$notification_email = array_merge( $defaults, $notification_email );
-	} else {
-		$notification_email = $defaults;
-	}
-
-	list( $to, $subject, $message, $headers ) = array_values( $notification_email );
+	$notification_email = array_merge( $defaults, (array) $notification_email );
 
-	$subject = wp_specialchars_decode( $subject );
+	$mail_success = WP_Mailer::send(
+		'retrieve_password',
+		array(
+			'to'      => $notification_email[ 'to' ],
+			'headers' => $notification_email[ 'headers' ],
+		),
+		array_merge(
+			$email_data,
+			array(
+				// Overwrite subject and body if they were filtered.
+				'subject' => $notification_email[ 'subject' ],
+				'body'    => $notification_email[ 'message' ],
+			)
+		)
+	);
 
-	if ( ! wp_mail( $to, $subject, $message, $headers ) ) {
+	if ( ! $mail_success ) {
 		$errors->add(
 			'retrieve_password_email_failure',
 			sprintf(
diff --git a/src/wp-settings.php b/src/wp-settings.php
index dab1d8fd4c0de..9593ac0a7c695 100644
--- a/src/wp-settings.php
+++ b/src/wp-settings.php
@@ -47,6 +47,7 @@
 require ABSPATH . WPINC . '/class-wp-recovery-mode-key-service.php';
 require ABSPATH . WPINC . '/class-wp-recovery-mode-link-service.php';
 require ABSPATH . WPINC . '/class-wp-recovery-mode-email-service.php';
+require ABSPATH . WPINC . '/class-wp-mailer.php';
 require ABSPATH . WPINC . '/class-wp-recovery-mode.php';
 require ABSPATH . WPINC . '/error-protection.php';
 require ABSPATH . WPINC . '/default-constants.php';
diff --git a/tests/phpunit/tests/mail/wpMailer.php b/tests/phpunit/tests/mail/wpMailer.php
new file mode 100644
index 0000000000000..6529290a8d108
--- /dev/null
+++ b/tests/phpunit/tests/mail/wpMailer.php
@@ -0,0 +1,183 @@
+<?php
+/**
+ * @group mail
+ * @covers WP_Mailer
+ */
+class Tests_Mail_WP_Mailer extends WP_UnitTestCase {
+
+	public function set_up() {
+		parent::set_up();
+		reset_phpmailer_instance();
+	}
+
+	public function tear_down() {
+		reset_phpmailer_instance();
+		parent::tear_down();
+	}
+
+	/**
+	 * Tests the render method.
+	 */
+	public function test_render() {
+		$template = 'Hello {{name}}, welcome to {{site}}!';
+		$data     = array(
+			'name' => 'Alice',
+			'site' => 'WordPress',
+		);
+		$expected = 'Hello Alice, welcome to WordPress!';
+		$this->assertSame( $expected, WP_Mailer::render( $template, $data ) );
+	}
+
+	/**
+	 * Tests the render method with missing data.
+	 */
+	public function test_render_missing_data() {
+		$template = 'Hello {{name}}, welcome to {{site}}!';
+		$data     = array(
+			'name' => 'Alice',
+		);
+		$expected = 'Hello Alice, welcome to {{site}}!';
+		$this->assertSame( $expected, WP_Mailer::render( $template, $data ) );
+	}
+
+	/**
+	 * Tests sending an email with registered template.
+	 */
+	public function test_send_registered_email() {
+		WP_Mailer::register_email(
+			'test_email',
+			'test_group',
+			array(
+				'subject' => 'Subject for {{name}}',
+				'body'    => 'Body for {{name}} at {{site}}',
+			)
+		);
+
+		WP_Mailer::send(
+			'test_email',
+			array( 'to' => 'test@example.com' ),
+			array(
+				'name' => 'Bob',
+				'site' => 'Example Site',
+			)
+		);
+
+		$mailer = tests_retrieve_phpmailer_instance();
+		$this->assertSame( 'Subject for Bob', $mailer->Subject );
+		$this->assertStringContainsString( 'Body for Bob at Example Site', $mailer->get_sent()->body );
+	}
+
+	/**
+	 * Tests the Reply-To fix in wp_mail.
+	 *
+	 * @ticket 49661
+	 */
+	public function test_wp_mail_reply_to_quoting_fix() {
+		$to       = 'recipient@example.com';
+		$subject  = 'Testing Reply-To';
+		$message  = 'Message body';
+		$headers  = 'Reply-To: "John Doe" <john@example.com>';
+
+		wp_mail( $to, $subject, $message, $headers );
+
+		$mailer    = tests_retrieve_phpmailer_instance();
+		$reply_tos = $mailer->getReplyToAddresses();
+
+		$this->assertCount( 1, $reply_tos );
+		$reply_to = reset( $reply_tos );
+
+		// PHPMailer will add its own quotes if needed, but we should not have double quotes here.
+		$this->assertSame( 'john@example.com', $reply_to[ 0 ] );
+		$this->assertSame( 'John Doe', $reply_to[ 1 ] );
+	}
+
+	/**
+	 * Tests the retrieve_password template logic.
+	 */
+	public function test_retrieve_password_template() {
+		$site_name  = 'My Awesome Site';
+		$user_login = 'alice';
+		$reset_url  = 'https://example.com/reset';
+		$ip         = '127.0.0.1';
+
+		WP_Mailer::register_email(
+			'retrieve_password',
+			'user',
+			array(
+				'subject' => '[{{sitename}}] Password Reset',
+				'body'    => 'Username: {{user_login}} Reset: {{reset_url}} IP: {{ip_notification}}',
+			)
+		);
+
+		WP_Mailer::send(
+			'retrieve_password',
+			array( 'to' => 'alice@example.com' ),
+			array(
+				'sitename'        => $site_name,
+				'user_login'      => $user_login,
+				'reset_url'       => $reset_url,
+				'ip_notification' => $ip,
+			)
+		);
+
+		$mailer = tests_retrieve_phpmailer_instance();
+		$this->assertSame( '[' . $site_name . '] Password Reset', $mailer->Subject );
+		$this->assertStringContainsString( 'Username: alice', $mailer->get_sent()->body );
+		$this->assertStringContainsString( 'Reset: https://example.com/reset', $mailer->get_sent()->body );
+		$this->assertStringContainsString( 'IP: 127.0.0.1', $mailer->get_sent()->body );
+	}
+
+	/**
+	 * Tests the new_user templates.
+	 */
+	public function test_new_user_templates() {
+		// Admin notification.
+		WP_Mailer::register_email(
+			'new_user_admin',
+			'admin',
+			array(
+				'subject' => '[{{sitename}}] New User',
+				'body'    => 'User: {{user_login}} Email: {{user_email}}',
+			)
+		);
+
+		WP_Mailer::send(
+			'new_user_admin',
+			array( 'to' => 'admin@example.com' ),
+			array(
+				'sitename'   => 'Site',
+				'user_login' => 'bob',
+				'user_email' => 'bob@example.com',
+			)
+		);
+
+		$mailer = tests_retrieve_phpmailer_instance();
+		$this->assertSame( '[Site] New User', $mailer->Subject );
+		$this->assertStringContainsString( 'User: bob', $mailer->get_sent()->body );
+
+		// User notification.
+		reset_phpmailer_instance();
+		WP_Mailer::register_email(
+			'new_user',
+			'user',
+			array(
+				'subject' => '[{{sitename}}] Login Details',
+				'body'    => 'Login: {{user_login}} URL: {{set_password_url}}',
+			)
+		);
+
+		WP_Mailer::send(
+			'new_user',
+			array( 'to' => 'bob@example.com' ),
+			array(
+				'sitename'         => 'Site',
+				'user_login'       => 'bob',
+				'set_password_url' => 'http://example.com/set-pw',
+			)
+		);
+
+		$mailer = tests_retrieve_phpmailer_instance();
+		$this->assertSame( '[Site] Login Details', $mailer->Subject );
+		$this->assertStringContainsString( 'URL: http://example.com/set-pw', $mailer->get_sent()->body );
+	}
+}