The remote certificate is invalid according to the validation procedure

using System.Net.Security;
using System;
using Limilabs.Mail;
using Limilabs.Client.IMAP;

internal class Program
{
    private static void Main(string[] args)
    {
        using (Imap client = new Imap())
        {
            // Use custom certificate validation:
            client.ServerCertificateValidate +=
                new ServerCertificateValidateEventHandler(Validate);

            // Minimalistic version to accept any certificate:
            // 
            // client.ServerCertificateValidate +=
            //    (sender, e) => { e.IsValid = true; };

            client.ConnectSSL("server.example.com");
            client.UseBestLogin("user", "password");

            foreach (long uid in client.GetAll())
            {
                var eml = client.GetMessageByUID(uid);
                IMail email = new MailBuilder()
                    .CreateFromEml(eml);

                Console.WriteLine("subject: {0}", email.Subject);
            }

            client.Close();
        }
    }

    private static void Validate(
        object sender,
        ServerCertificateValidateEventArgs e)
    {
        const SslPolicyErrors ignoredErrors =
            // self-signed
            SslPolicyErrors.RemoteCertificateChainErrors
            // name mismatch
            |  SslPolicyErrors.RemoteCertificateNameMismatch;  

        string nameOnCertificate = e.Certificate.Subject;

        if ((e.SslPolicyErrors & ~ignoredErrors) 
            == SslPolicyErrors.None)
        {
            e.IsValid = true;
            return;
        }
        e.IsValid = false;
    }
} ;

Imports System.Net.Security
Imports System
Imports Limilabs.Mail
Imports Limilabs.Client.IMAP

Public Module Module1

  Public Sub Main(ByVal args As String())
    Using client As New Imap()
      ' Use custom certificate validation:
      AddHandler client.ServerCertificateValidate, AddressOf Validate

      client.ConnectSSL("server.example.com")
      client.UseBestLogin("user", "password")

      For Each uid As Long In client.GetAll()
        Dim email As IMail = New MailBuilder().CreateFromEml( _
          client.GetMessageByUID(uid))

        Console.WriteLine("subject: {0}", email.Subject)
      Next

      client.Close()
    End Using
  End Sub

  Private Sub Validate( _
     ByVal sender As Object, _
     ByVal e As ServerCertificateValidateEventArgs)

     Const ignoredErrors As SslPolicyErrors = _
          ' self-signed
          SslPolicyErrors.RemoteCertificateChainErrors _
          ' name mismatch
          Or SslPolicyErrors.RemoteCertificateNameMismatch        

     Dim nameOnCertificate As String = e.Certificate.Subject

      If (e.SslPolicyErrors And Not ignoredErrors) = SslPolicyErrors.None Then
         e.IsValid = True
         Return
      End If
      e.IsValid = False
  End Sub

End Module