SMTP Virtual Server and TLS configuration

Hi all,

if I bing for 530 5.7.0 Must issue a STARTTLS command first, there a few posts but no answer to my case!

This is the environment in my case:

Application Server --tcp 25 --> SMTP Relay Server --tcp 25 --> Exchange Server 201X

The goal is to get a TLS connection from application server to smtp relay server. The smpt virtual server is configured as follow:

- Outgoing security: TLS enc. is selected additionally to anonymous access
- General page > advanced is default

When I start 'smtp diag tool' on a smtp relay server and use following settings

The connection first works but it breaks with following error message:

This is the error message: Must issue a STARTTLS command first.

The SSL Certificate is issued for the smpt FQDN and is trusted by the smtp server. And in IIS the binding is correct. 

Thanks in advance!





Soheil