Created initial SMTP handlers.

__SMTP_MAIL.h

@@ -0,0 +1,25 @@
+      //---------------------------------------------------------------------------
+      // MAIL command request handling.
+      //---------------------------------------------------------------------------
+
+      else if(command(input) == "MAIL") {
+
+         sender = cleanEMail(input.substr(5));
+
+         //-------------------------------------------------------------
+         // Verify that the senders domain name resolves to an address
+         // with an MX record. If not and there is a bounce then we 
+         // will not be able to return the bounce message so it is
+         // probably a spammer anyway.
+         //-------------------------------------------------------------
+
+         if(verifyDomainMX(domainOnly(sender))) {
+
+            cout << "250 OK" << CRLF;
+            log.message("Response: 250 OK.");
+            recipientList = "";
+            state = "MAIL";
+         }
+
+
+      }