我有一个服务器(Centos 7)设置用作邮件服务器。使用 postfix/dovecot/opendkim/opendmarc.. 它可以正常工作,例如,用户可以使用 gmail 连接他们的电子邮件。能够收发邮件。
此外,当我使用 MailKit 并从我的家用电脑测试我的 .NET Core 应用程序时,MailKit 连接正常并且电子邮件已发送。
但是,当我将应用程序部署到我的服务器时,MailKit 无法连接。
如果我查看日志,我会看到以下内容
postfix/submission/smtpd[4486]: match_hostname: unknown ~? 127.0.0.1/32
postfix/submission/smtpd[4486]: match_hostaddr: MY_SERVER_IP ~? 127.0.0.1/32
postfix/submission/smtpd[4486]: match_hostname: unknown ~? MY_SERVER_IP/32
postfix/submission/smtpd[4486]: match_hostaddr: MY_SERVER_IP ~? MY_SERVER_IP/32
postfix/submission/smtpd[4486]: lost connection after STARTTLS from unknown[MY_SERVER_IP]
但是如果我在日志中看起来更高一点,我会看到
Anonymous TLS connection established from unknown[MY_SERVER_IP]: TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)
我的 MailKit(在服务器外部可以正常工作):
using (SmtpClient emailClient = new SmtpClient())
{
await emailClient.ConnectAsync(emailConfiguration.SmtpServer, emailConfiguration.SmtpPort, SecureSocketOptions.StartTls);
emailClient.AuthenticationMechanisms.Remove("XOAUTH2");
await emailClient.AuthenticateAsync(emailConfiguration.SmtpUsername, emailConfiguration.SmtpPassword);
await emailClient.SendAsync(message);
await emailClient.DisconnectAsync(true);
}
编辑:MailKit 的例外(证书是正确的,不是自签名的):
MailKit.Security.SslHandshakeException: An error occurred while attempting to establish an SSL or TLS connection.
May 19 16:07:37 domain.com NETCoreApp[4452]: The server's SSL certificate could not be validated for the following reasons:
May 19 16:07:37 domain.com NETCoreApp[4452]: • The server certificate has the following errors:
May 19 16:07:37 domain.com NETCoreApp[4452]: • unable to get certificate CRL
May 19 16:07:37 domain.com NETCoreApp[4452]: • The root certificate has the following errors:
May 19 16:07:37 domain.com NETCoreApp[4452]: • unable to get certificate CRL
May 19 16:07:37 domain.com NETCoreApp[4452]: • unable to get local issuer certificate
May 19 16:07:37 domain.com NETCoreApp[4452]: ---> System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure.