Failed to send email from 1and1 (ionos) hosting server using ASP .Net Core and Mailkit
问题 I have created a simple email service in my .Net Core application, which sends mail messages using provider email. It works just fine on my local machine with port 587. But when I published it to my 1and1 hosting server, it failed to send the email. Here is my little code, how I create client using the Mailkit : using(var client = new SmtpClient()) { client.ServerCertificateValidationCallback = (sender, certificate, certChainType, errors) => true; client.CheckCertificateRevocation = false;