diff --git a/tests/phpunit/tests/multisite.php b/tests/phpunit/tests/multisite.php
index 7427d9f35e..e93edbcbe5 100644
--- a/tests/phpunit/tests/multisite.php
+++ b/tests/phpunit/tests/multisite.php
@@ -36,37 +36,6 @@ class Tests_Multisite extends WP_UnitTestCase {
 		$reg_blog = $wpdb->get_col( "SELECT email FROM {$wpdb->registration_log} WHERE {$wpdb->registration_log}.blog_id = 1 AND IP LIKE '" . $ip . "'" );
 		$this->assertEquals( $user->user_email, $reg_blog[ count( $reg_blog )-1 ] );
 	}
-
-	/**
-	 * @ticket 21570
-	 */
-	function test_aggressiveness_of_is_email_address_unsafe() {
-		update_site_option( 'banned_email_domains', array( 'bar.com', 'foo.co' ) );
-
-		foreach ( array( 'test@bar.com', 'test@foo.bar.com', 'test@foo.co', 'test@subdomain.foo.co' ) as $email_address ) {
-			$this->assertTrue( is_email_address_unsafe( $email_address ), "$email_address should be UNSAFE" );
-		}
-
-		foreach ( array( 'test@foobar.com', 'test@foo-bar.com', 'test@foo.com', 'test@subdomain.foo.com' ) as $email_address ) {
-			$this->assertFalse( is_email_address_unsafe( $email_address ), "$email_address should be SAFE" );
-		}
-	}
-
-	/**
-	 * @ticket 25046
-	 */
-	function test_case_sensitivity_of_is_email_address_unsafe() {
-		update_site_option( 'banned_email_domains', array( 'baR.com', 'Foo.co', 'barfoo.COM', 'BAZ.com' ) );
-
-		foreach ( array( 'test@Bar.com', 'tEst@bar.com', 'test@barFoo.com', 'tEst@foo.bar.com', 'test@baz.Com' ) as $email_address ) {
-			$this->assertTrue( is_email_address_unsafe( $email_address ), "$email_address should be UNSAFE" );
-		}
-
-		foreach ( array( 'test@Foobar.com', 'test@Foo-bar.com', 'tEst@foobar.com', 'test@Subdomain.Foo.com', 'test@fooBAz.com' ) as $email_address ) {
-			$this->assertFalse( is_email_address_unsafe( $email_address ), "$email_address should be SAFE" );
-		}
-
-	}
 }
 
 endif;
diff --git a/tests/phpunit/tests/multisite/isEmailAddressUnsafe.php b/tests/phpunit/tests/multisite/isEmailAddressUnsafe.php
new file mode 100644
index 0000000000..51a29ef4d9
--- /dev/null
+++ b/tests/phpunit/tests/multisite/isEmailAddressUnsafe.php
@@ -0,0 +1,121 @@
+<?php
+
+/**
+ * @group multisite
+ */
+class Tests_Multisite_IsEmailAddressUnsafe extends WP_UnitTestCase {
+	public function test_string_domain_list_should_be_split_on_line_breaks() {
+		update_site_option( 'banned_email_domains', "foo.com\nbar.org\nbaz.gov" );
+		$this->assertTrue( is_email_address_unsafe( 'foo@bar.org' ) );
+		$this->assertFalse( is_email_address_unsafe( 'foo@example.org' ) );
+	}
+
+	/**
+	 * @dataProvider data_unsafe
+	 * @ticket 25046
+	 * @ticket 21570
+	 */
+	public function test_unsafe_emails( $banned, $email ) {
+		update_site_option( 'banned_email_domains', $banned );
+		$this->assertTrue( is_email_address_unsafe( $email ) );
+	}
+
+	/**
+	 * @dataProvider data_safe
+	 * @ticket 25046
+	 * @ticket 21570
+	 */
+	public function test_safe_emails( $banned, $email ) {
+		update_site_option( 'banned_email_domains', $banned );
+		$this->assertFalse( is_email_address_unsafe( $email ) );
+	}
+
+	public function data_unsafe() {
+		return array(
+			// 25046
+			'case_insensitive_1' => array(
+				array( 'baR.com' ),
+				'test@Bar.com',
+			),
+			'case_insensitive_2' => array(
+				array( 'baR.com' ),
+				'tEst@bar.com',
+			),
+			'case_insensitive_3' => array(
+				array( 'barfoo.COM' ),
+				'test@barFoo.com',
+			),
+			'case_insensitive_4' => array(
+				array( 'baR.com' ),
+				'tEst@foo.bar.com',
+			),
+			'case_insensitive_5' => array(
+				array( 'BAZ.com' ),
+				'test@baz.Com',
+			),
+
+
+			// 21570
+			array(
+				array( 'bar.com', 'foo.co' ),
+				'test@bar.com',
+			),
+			'subdomain_1' => array(
+				array( 'bar.com', 'foo.co' ),
+				'test@foo.bar.com',
+			),
+			array(
+				array( 'bar.com', 'foo.co' ),
+				'test@foo.co',
+			),
+			'subdomain_2' => array(
+				array( 'bar.com', 'foo.co' ),
+				'test@subdomain.foo.co',
+			),
+		);
+	}
+
+	public function data_safe() {
+		return array(
+			// 25046
+			array(
+				array( 'baR.com', 'Foo.co', 'barfoo.COM', 'BAZ.com' ),
+				'test@Foobar.com',
+			),
+			array(
+				array( 'baR.com', 'Foo.co', 'barfoo.COM', 'BAZ.com' ),
+				'test@Foo-bar.com',
+			),
+			array(
+				array( 'baR.com', 'Foo.co', 'barfoo.COM', 'BAZ.com' ),
+				'tEst@foobar.com',
+			),
+			array(
+				array( 'baR.com', 'Foo.co', 'barfoo.COM', 'BAZ.com' ),
+				'test@Subdomain.Foo.com',
+			),
+			array(
+				array( 'baR.com', 'Foo.co', 'barfoo.COM', 'BAZ.com' ),
+				'test@feeBAz.com',
+			),
+
+			// 21570
+			array(
+				array( 'bar.com', 'foo.co' ),
+				'test@foobar.com',
+			),
+			array(
+				array( 'bar.com', 'foo.co' ),
+				'test@foo-bar.com',
+			),
+			array(
+				array( 'bar.com', 'foo.co' ),
+				'test@foo.com',
+			),
+			array(
+				array( 'bar.com', 'foo.co' ),
+				'test@subdomain.foo.com',
+			),
+		);
+	}
+}