feat: add option to control CheckCertificateRevocation flag of MailKit

Author: sdellaco

Rnwood.Smtp4dev/Server/Settings/RelayOptions.cs

@@ -26,6 +26,8 @@ public int SmtpPort
         public SecureSocketOptions TlsMode { get; set; } = SecureSocketOptions.Auto;
 
         public string[] SslCipherSuitesPolicy { get; set; } = System.Array.Empty<string>();
+
+        public bool CheckCertificateRevocation { get; set; } = true;
 
         public string[] AutomaticEmails { get; set; } = System.Array.Empty<string>();
 

Rnwood.Smtp4dev/Server/Settings/RelayOptionsSource.cs

@@ -20,6 +20,8 @@ public int? SmtpPort
 
         public string[] SslCipherSuitesPolicy { get; set; } = System.Array.Empty<string>();
 
+        public bool CheckCertificateRevocation { get; set; } = true;
+        
         public string[] AutomaticEmails { get; set; } = System.Array.Empty<string>();
 
         public string AutomaticRelayExpression { get; set; }

Rnwood.Smtp4dev/Startup.cs

@@ -255,6 +255,7 @@ public void ConfigureServices(IServiceCollection services)
                     }
                 }
 #endif
+                result.CheckCertificateRevocation = relayOptions.CheckCertificateRevocation;
                 result.Connect(relayOptions.SmtpServer, relayOptions.SmtpPort, relayOptions.TlsMode);
 
                 if (!string.IsNullOrEmpty(relayOptions.Login))