diff --git a/lng/english.lng.php b/lng/english.lng.php
index 507799e7..d514eddc 100644
--- a/lng/english.lng.php
+++ b/lng/english.lng.php
@@ -226,7 +226,7 @@ $lng['error']['emailexistalready'] = 'The email-address %s already exists.';
 $lng['error']['maindomainnonexist'] = 'The main-domain %s does not exist.';
 $lng['error']['destinationnonexist'] = 'Please create your forwarder in the field \'Destination\'.';
 $lng['error']['destinationalreadyexistasmail'] = 'The forwarder to %s already exists as active email-address.';
-$lng['error']['destinationalreadyexist'] = 'You have already defined a forwarder to %s .';
+$lng['error']['destinationalreadyexist'] = 'You have already defined a forwarder to "%s"';
 $lng['error']['destinationiswrong'] = 'The forwarder %s contains invalid character(s) or is incomplete.';
 $lng['error']['ticketnotaccessible'] = 'You cannot access this ticket.';
 
diff --git a/tests/Emails/EmailsTest.php b/tests/Emails/EmailsTest.php
index 77f71c12..73287358 100644
--- a/tests/Emails/EmailsTest.php
+++ b/tests/Emails/EmailsTest.php
@@ -5,9 +5,12 @@ use PHPUnit\Framework\TestCase;
  * @covers ApiCommand
  * @covers ApiParameter
  * @covers Emails
+ * @covers EmailForwarders
+ * @covers EmailAccounts
  */
 class MailsTest extends TestCase
 {
+
 	public function testCustomerEmailsAdd()
 	{
 		global $admin_userdata;
@@ -27,7 +30,7 @@ class MailsTest extends TestCase
 		$this->assertEquals("info@test2.local", $result['email_full']);
 		$this->assertEquals(0, $result['iscatchall']);
 	}
-	
+
 	public function testAdminEmailsAdd()
 	{
 		global $admin_userdata;
@@ -42,4 +45,199 @@ class MailsTest extends TestCase
 		$this->assertEquals("catchall@test2.local", $result['email_full']);
 		$this->assertEquals(1, $result['iscatchall']);
 	}
+
+	public function testAdminEmailsUpdate()
+	{
+		global $admin_userdata;
+		$data = [
+			'emailaddr' => 'catchall@test2.local',
+			'iscatchall' => 0,
+			'customerid' => 1
+		];
+		$json_result = Emails::getLocal($admin_userdata, $data)->update();
+		$result = json_decode($json_result, true)['data'];
+		$this->assertEquals(0, $result['iscatchall']);
+	}
+
+	public function testCustomerEmailsUpdate()
+	{
+		global $admin_userdata;
+		
+		// get customer
+		$json_result = Customers::getLocal($admin_userdata, array(
+			'loginname' => 'test1'
+		))->get();
+		$customer_userdata = json_decode($json_result, true)['data'];
+		
+		$data = [
+			'emailaddr' => 'catchall@test2.local',
+			'iscatchall' => 1
+		];
+		$json_result = Emails::getLocal($customer_userdata, $data)->update();
+		$result = json_decode($json_result, true)['data'];
+		$this->assertEquals(1, $result['iscatchall']);
+	}
+
+	public function testCustomerEmailForwardersAdd()
+	{
+		global $admin_userdata;
+		
+		// get customer
+		$json_result = Customers::getLocal($admin_userdata, array(
+			'loginname' => 'test1'
+		))->get();
+		$customer_userdata = json_decode($json_result, true)['data'];
+		
+		$data = [
+			'emailaddr' => 'info@test2.local',
+			'destination' => 'other@domain.tld'
+		];
+		$json_result = EmailForwarders::getLocal($customer_userdata, $data)->add();
+		$result = json_decode($json_result, true)['data'];
+		$this->assertEquals('other@domain.tld', $result['destination']);
+	}
+
+	public function testCustomerEmailForwardersAddAnother()
+	{
+		global $admin_userdata;
+		
+		// get customer
+		$json_result = Customers::getLocal($admin_userdata, array(
+			'loginname' => 'test1'
+		))->get();
+		$customer_userdata = json_decode($json_result, true)['data'];
+		
+		$data = [
+			'emailaddr' => 'info@test2.local',
+			'destination' => 'other2@domain.tld'
+		];
+		$json_result = EmailForwarders::getLocal($customer_userdata, $data)->add();
+		$result = json_decode($json_result, true)['data'];
+		$this->assertEquals('other@domain.tld other2@domain.tld', $result['destination']);
+	}
+
+	/**
+	 * @depends testCustomerEmailForwardersAdd
+	 */
+	public function testCustomerEmailForwardersAddExistingAsMail()
+	{
+		global $admin_userdata;
+		
+		// get customer
+		$json_result = Customers::getLocal($admin_userdata, array(
+			'loginname' => 'test1'
+		))->get();
+		$customer_userdata = json_decode($json_result, true)['data'];
+		
+		$data = [
+			'emailaddr' => 'info@test2.local',
+			'destination' => 'info@test2.local'
+		];
+		$this->expectExceptionMessage("The forwarder to info@test2.local already exists as active email-address.");
+		EmailForwarders::getLocal($customer_userdata, $data)->add();
+	}
+
+	/**
+	 * @depends testCustomerEmailForwardersAdd
+	 */
+	public function testCustomerEmailForwardersAddExistingAsDestination()
+	{
+		global $admin_userdata;
+		
+		// get customer
+		$json_result = Customers::getLocal($admin_userdata, array(
+			'loginname' => 'test1'
+		))->get();
+		$customer_userdata = json_decode($json_result, true)['data'];
+		
+		$data = [
+			'emailaddr' => 'info@test2.local',
+			'destination' => 'other@domain.tld'
+		];
+		$this->expectExceptionMessage('You have already defined a forwarder to "other@domain.tld"');
+		EmailForwarders::getLocal($customer_userdata, $data)->add();
+	}
+
+	public function testCustomerEmailForwardersAddInvalid()
+	{
+		global $admin_userdata;
+		
+		// get customer
+		$json_result = Customers::getLocal($admin_userdata, array(
+			'loginname' => 'test1'
+		))->get();
+		$customer_userdata = json_decode($json_result, true)['data'];
+		
+		$data = [
+			'emailaddr' => 'info@test2.local',
+			'destination' => '@domain.com'
+		];
+		$this->expectExceptionMessage("The forwarder domain.com contains invalid character(s) or is incomplete.");
+		EmailForwarders::getLocal($customer_userdata, $data)->add();
+	}
+
+	public function testAdminEmailForwadersUndefinedGet()
+	{
+		global $admin_userdata;
+		$this->expectExceptionCode(303);
+		EmailForwarders::getLocal($admin_userdata)->get();
+	}
+
+	public function testAdminEmailForwadersUndefinedUpdate()
+	{
+		global $admin_userdata;
+		$this->expectExceptionCode(303);
+		EmailForwarders::getLocal($admin_userdata)->update();
+	}
+
+	public function testAdminEmailForwadersUndefinedListing()
+	{
+		global $admin_userdata;
+		$this->expectExceptionCode(303);
+		EmailForwarders::getLocal($admin_userdata)->listing();
+	}
+
+	/**
+	 * @depends testCustomerEmailForwardersAddAnother
+	 */
+	public function testCustomerEmailForwardersDelete()
+	{
+		global $admin_userdata;
+		
+		// get customer
+		$json_result = Customers::getLocal($admin_userdata, array(
+			'loginname' => 'test1'
+		))->get();
+		$customer_userdata = json_decode($json_result, true)['data'];
+		
+		$data = [
+			'emailaddr' => 'info@test2.local',
+			'forwarderid' => 1
+		];
+		$json_result = EmailForwarders::getLocal($customer_userdata, $data)->delete();
+		$result = json_decode($json_result, true)['data'];
+		$this->assertEquals('other@domain.tld', $result['destination']);
+	}
+
+	/**
+	 * @depends testCustomerEmailForwardersAddAnother
+	 */
+	public function testCustomerEmailForwardersDeleteunknown()
+	{
+		global $admin_userdata;
+		
+		// get customer
+		$json_result = Customers::getLocal($admin_userdata, array(
+			'loginname' => 'test1'
+		))->get();
+		$customer_userdata = json_decode($json_result, true)['data'];
+		
+		$data = [
+			'emailaddr' => 'info@test2.local',
+			'forwarderid' => 1337
+		];
+		$this->expectExceptionCode(404);
+		$this->expectExceptionMessage("Unknown forwarder id");
+		EmailForwarders::getLocal($customer_userdata, $data)->delete();
+	}
 }