Das Remotezertifikat ist laut Validierungsverfahren ungultig

Question

We try to send emails with the mail.dll over an exchange Server.

The Server is in the local network. We don´t need any username or passwort usally to send over this specific server. But we get the following message.
Maybe you can help us to find the right way.

System.Security.Authentication.AuthenticationException: Das Remotezertifikat ist laut Validierungsverfahren ungültig.

bei System.Net.Security.SslState.StartSendAuthResetSignal(ProtocolToken message, AsyncProtocolRequest asyncRequest, Exception exception)

Answer 1

The translation of this error to English is "The remote certificate is invalid according to the validation procedure".

This error means that there was a problem with the SSL certificate send by the server while SSL or TLS connection was being established.

Most likely the server certificate is self-signed or you are using incorrect host name to connect (e.g. "example.com" instead of "smtp.example.com").

If you are using self-signed certificates you can accept those using ServerCertificateValidate event.

Please read this article for details:
https://www.limilabs.com/blog/the-remote-certificate-is-invalid-according-to-the-validation-procedure