feat: Allow NoAuthentication for OnPremise MAIL destination

.changeset/angry-ways-kneel.md

@@ -0,0 +1,5 @@
+---
+'@sap-cloud-sdk/mail-client': minor
+---
+
+Allow NoAuthentication for OnPremise MAIL destination

packages/mail-client/src/mail-client.spec.ts

@@ -128,6 +128,53 @@ describe('mail client', () => {
     ).resolves.not.toThrow();
   });
 
+  it('should work with destination from service - proxy-type OnPremise with Authentication set to NoAuthentication', async () => {
+    const { connection } = mockSocketConnection();
+    jest
+      .spyOn(nodemailer, 'createTransport')
+      .mockReturnValue(mockTransport as any);
+
+    jest.spyOn(mockTransport, 'sendMail').mockImplementation(() => {
+      connection.socket.on('data', () => {});
+    });
+
+    const mailOptions1: MailConfig = {
+      from: '[email protected]',
+      to: '[email protected]'
+    };
+
+    const mailClientOptions: MailClientOptions = {
+      tls: {
+        rejectUnauthorized: false
+      }
+    };
+
+    const mailDestinationResponse: DestinationConfiguration = {
+      Name: 'MyMailDestination',
+      Type: 'MAIL',
+      Authentication: 'NoAuthentication',
+      ProxyType: 'OnPremise',
+      'mail.smtp.host': 'smtp.gmail.com',
+      'mail.smtp.port': '587'
+    };
+
+    mockServiceBindings();
+    // the mockServiceToken() method does not work outside connectivity module.
+    jest
+      .spyOn(tokenAccessor, 'serviceToken')
+      .mockImplementation(() => Promise.resolve(providerServiceToken));
+
+    mockFetchDestinationCalls(mailDestinationResponse);
+
+    await expect(
+      sendMail(
+        { destinationName: mailDestinationResponse.Name },
+        [mailOptions1],
+        mailClientOptions
+      )
+    ).resolves.not.toThrow();
+  });
+
   it('should work with registered destination', async () => {
     jest
       .spyOn(nodemailer, 'createTransport')

packages/mail-client/src/mail-client.ts

@@ -76,6 +76,12 @@ function getCredentials(
   destination: Destination,
   originalProperties: Record<string, any>
 ): { username: string; password: string } {
+  if (
+    destination.proxyType === 'OnPremise' &&
+    destination.authentication === 'NoAuthentication'
+  ) {
+    return { username: '', password: '' };
+  }
   const username = originalProperties['mail.user'];
   const password = originalProperties['mail.password'];