Verifies the certificate contained the address of the server, which is not equal to the address of the proxy server, hence the error. I had the same error when i tried to send email using SmtpClient via proxy server (Usergate). for default Exchange server installations, so return true. untrusted root errors for self-signed certificates.

When processing reaches this line, the only errors in the certificate chain are If there are any other errors in the certificate chain, the certificate is invalid, Self-signed certificates with an untrusted root are valid. If ((certificate.Subject = certificate.Issuer) &

If (chain != null & chain.ChainStatus != null)įoreach (509Certificates.X509ChainStatus status in chain.ChainStatus) If ((sslPolicyErrors & .RemoteCertificateChainErrors) != 0)

If there are errors in the certificate chain, look at each error to determine the cause. If the certificate is a valid, signed certificate, return true. 509Certificates.X509Certificate certificate, The code we use (courtesy of Microsoft - (v=exchg.80).aspx) is as follows: private static bool CertificateValidationCallBack( You could obviously check for other SSL errors if you so desired. at .StartSendAuthResetSignal(ProtocolToken message, AsyncProtocolRequest asyncRequest, Exception exception)Īt .CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)Īt .StartSendBlob(Byte incoming, Int32 count, AsyncProtocolRequest asyncRequest)Īt .ProcessReceivedBlob(Byte buffer, Int32 count, AsyncProtocolRequest asyncRequest)Īt .StartReadFrame(Byte buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)Īt .StartReceiveBlob(Byte buffer, AsyncProtocolRequest asyncRequest)Īt .ForceAuthentication(Boolean receiveFirst, Byte buffer, AsyncProtocolRequest asyncRequest)Īt .ProcessAuthentication(LazyAsyncResult lazyResult)Īt (Object state)Īt (ExecutionContext executionContext, ContextCallback callback, Object state)Īt (LazyAsyncResult result)Īt (Byte buffer, Int32 offset, Int32 size)Īt (Byte buffer, Int32 offset, Int32 size)Īt .Flush()Īt .GetConnection(String host, Int32 port)Īt .GetConnection(String host, Int32 port)Īt .GetConnection()Īt .Send(MailMessage message)Īt (String toaddress, String fromaddress, String fromname, String subject, String pwd, String attachements, String mailmessage, String htmlmessage, Int32 i, Int32 j, String replytoaddress)Ī little late to the party, but if you are looking for a solution like Yury's the following code will help you identify if the issue is related to a self-sign certificate and, if so ignore the self-sign error. Whenever I try to send e-mail using Gmail's SMTP server in my C# code.Ĭan someone point me to the right direction for a solution to this problem?

The remote certificate is invalid according to the validation procedure.

Avast server certificate invalid