CODEWITHSUNDEEP
c#emailasp.net-coresmtp
Mohaned Ghawar
Mohaned Ghawar

Reputation: 11

Getting error while sending email in Asp.net core ( An error occurred while attempting to establish an SSL or TLS connection. )

I am workin on project using asp.net core 3.1 , also i am using design pattern in my work.

when i try to send email using smtp i got this error .

An error occurred while attempting to establish an SSL or TLS connection. The server's SSL certificate could not be validated for the following reasons: • The server certificate has the following errors: • The revocation function was unable to check revocation for the certificate.

This is my code ...

using (var client = new SmtpClient())
        {
            try
            {
                await client.ConnectAsync(_mailSettings.Host, _mailSettings.Port, false);
                client.AuthenticationMechanisms.Remove("XOAUTH2");
                await client.AuthenticateAsync(_mailSettings.UserName, _mailSettings.Password);
                await client.SendAsync(mailMessage);
            }
            catch
            {

                throw;
            }
            finally
            {
                await client.DisconnectAsync(true);
                client.Dispose();
            }

        }

the error happened after this line ...

 await client.ConnectAsync(_mailSettings.Host, _mailSettings.Port, false);

Upvotes: 2

Views: 5754

Answers (1)

jstedfast
jstedfast

Reputation: 38528

The revocation function was unable to check revocation for the certificate.

This is usually a transient error caused by the CRL server being offline or otherwise unreachable at the time when you tried to establish and SSL/TLS connection and so the SslStream was unable to validate the server's SSL certificate.

The CRL server is the central authority that provides a way for clients to check if a certificate has been revoked or not.

You can disable certificate revocation checks using the following snippet of code before calling the Connect method:

client.CheckCertificateRevocation = false;

For more information, see the documentation: http://www.mimekit.net/docs/html/P_MailKit_IMailService_CheckCertificateRevocation.htm

Upvotes: 9

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