diff --git a/src/wp-includes/pluggable.php b/src/wp-includes/pluggable.php
index 2ec21126e0..5ab3eef749 100644
--- a/src/wp-includes/pluggable.php
+++ b/src/wp-includes/pluggable.php
@@ -307,7 +307,7 @@ if ( ! function_exists( 'wp_mail' ) ) :
 							if ( false !== $bracket_pos ) {
 								// Text before the bracketed email is the "From" name.
 								if ( $bracket_pos > 0 ) {
-									$from_name = substr( $content, 0, $bracket_pos - 1 );
+									$from_name = substr( $content, 0, $bracket_pos );
 									$from_name = str_replace( '"', '', $from_name );
 									$from_name = trim( $from_name );
 								}
diff --git a/tests/phpunit/tests/mail.php b/tests/phpunit/tests/mail.php
index 718a585673..c130658e3f 100644
--- a/tests/phpunit/tests/mail.php
+++ b/tests/phpunit/tests/mail.php
@@ -193,6 +193,28 @@ class Tests_Mail extends WP_UnitTestCase {
 		$this->assertStringContainsString( $expected, $mailer->get_sent()->header );
 	}
 
+	/**
+	 * @ticket 19847
+	 */
+	public function test_wp_mail_with_from_header_missing_space() {
+		$to        = 'address@tld.com';
+		$subject   = 'Testing';
+		$message   = 'Test Message';
+		$from      = 'bar@example.com';
+		$from_name = 'Foo';
+		$headers   = "From: {$from_name}<{$from}>";
+		$corrected = "From: {$from_name} <{$from}>";
+
+		wp_mail( $to, $subject, $message, $headers );
+
+		$mailer = tests_retrieve_phpmailer_instance();
+		// phpcs:disable WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase
+		$this->assertSame( $from, $mailer->From );
+		$this->assertSame( $from_name, $mailer->FromName );
+		// phpcs:enable
+		$this->assertStringContainsString( $corrected, $mailer->get_sent()->header );
+	}
+
 	/**
 	 * @ticket 30266
 	 */