Unexpected SMTP server response. Expected: 220, actual: 500

Exchange 2012 version 15.0 on server 2012

Getting the following error message when i run the Remote connectivity Analyzer.  I have made adjustments to the auth mechanisms but have not been able to resolve the issue.

Also, every once in a while, I get the 451 local error.  I immediately rerun the test and everything works.  I mention this because there are times that email gets rejected with "#5.4.4 smtp;554 5.4.4 SMTPSEND.DNS.NonExistentDomain; nonexistent domain".  It is unpattered and happens a few times during the day.



Testing inbound SMTP mail flow for domain ME@Mycomp.com
 Inbound SMTP mail flow was verified successfully.
 
Test Steps
 
Attempting to retrieve DNS MX records for domain Mycomp.com.
 One or more MX records were successfully retrieved from DNS.
 
Additional Details
 MX Records Host server.mycomp.com, Preference 10



Testing Mail Exchanger server.mycomp.com.
 This Mail Exchanger was tested successfully.
 
Test Steps
 
Attempting to resolve the host name server.mycomp.com in DNS.
 The host name resolved successfully.
 
Additional Details
 IP addresses returned: XX.XX.XX.XX


Testing TCP port 25 on host server.mycomp.com to ensure it's listening and open.
 The port was opened successfully.
 
Additional Details
 Banner received: 220 server.mycomp.com Microsoft ESMTP MAIL Service ready at Mon, 1 Jul 2013 12:50:25 -0500


Analyzing SMTP Capabilities for server server.mycomp.com:25
 The test passed with some warnings encountered. Please expand the additional details.
 
Additional Details
 Unabled to determine SMTP capabilities. Reason: Unexpected SMTP server response. Expected: 220, actual: 500, whole response: 500 5.3.3 Unrecognized command



Attempting to send a test email message to me@mycomp.com using MX server.mycomp.com.
 The test email message was delivered successfully.

Testing the MX server.mycomp.com for open relay by trying to relay to user Admin@TestExchangeConnectivity.com.
 The Open Relay test passed. This MX isn't an open relay.
 
Additional Details
 The open relay test message delivery failed, which is a good thing.
The exception detail:
Exception details:
Message: Mailbox unavailable. The server response was: 5.7.1 Unable to relay
Type: System.Net.Mail.SmtpFailedRecipientException
Stack trace:
at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception)
at System.Net.Mail.SmtpClient.Send(MailMessage message)
at Microsoft.Exchange.Tools.ExRca.Tests.SmtpOpenRelayTest.PerformTestReally()

Thanks a bunch in advance