SMTP Error - unable to setup mail

1

I am using a private mailserver with SMTP on port 587 (my ISP blocks port 25). Whenever I try to connect I get the following error in Manager (v20.10.72):

System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure: RemoteCertificateNameMismatch, RemoteCertificateChainErrors
at System.Net.Security.SslStream.SendAuthResetSignal(ProtocolToken message, ExceptionDispatchInfo exception)
at System.Net.Security.SslStream.ForceAuthenticationAsync[TIOAdapter](TIOAdapter adapter, Boolean receiveFirst, Byte reAuthenticationData, Boolean isApm)
at System.Net.Security.SslStream.ProcessAuthentication(Boolean isAsync, Boolean isApm, CancellationToken cancellationToken)
at System.Net.Security.SslStream.AuthenticateAsClient(SslClientAuthenticationOptions sslClientAuthenticationOptions)
at System.Net.Security.SslStream.AuthenticateAsClient(String targetHost, X509CertificateCollection clientCertificates, SslProtocols enabledSslProtocols, Boolean checkCertificateRevocation)
at System.Net.TlsStream.AuthenticateAsClient()
at System.Net.Mail.SmtpConnection.GetConnection(String host, Int32 port)
at System.Net.Mail.SmtpTransport.GetConnection(String host, Int32 port)
at System.Net.Mail.SmtpClient.GetConnection()
at System.Net.Mail.SmtpClient.Send(MailMessage message)
at ManagerServer.HttpHandlers.Businesses.Business.Settings.EmailSettings.EmailTest.Post() in C:\projects\manager\ManagerServer\HttpHandlers\Businesses\Business\Settings\EmailSettings\EmailTest.cs:line 87
at ManagerServer.Startup.<>c.<b__1_1>d.MoveNext() in C:\projects\manager\ManagerServer\Startup.cs:line 87
— End of stack trace from previous location —
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)

2

Have you read the email troubleshooting Guide and followed all relevant links within it: Troubleshoot email issues | Manager? This is almost certainly a problem with your private mail server or ISP. Any possibility of help on this forum will require the information described in the Guide.