We help IT Professionals succeed at work.

We've partnered with Certified Experts, Carl Webster and Richard Faulkner, to bring you a podcast all about Citrix Workspace, moving to the cloud, and analytics & intelligence. Episode 2 coming soon!Listen Now


URGENT!  Unable to Send mail - message "550 Open relay not allowed"

FOSnet asked
Medium Priority
Last Modified: 2008-01-09
I am getting the following error Non delivery report when trying to send mail:

Your message did not reach some or all of the intended recipients.

      Subject:      RE:
      Sent:      06/11/2006 13:45

The following recipient(s) could not be reached:

      'Stephen.Gillham@fos.net' on 06/11/2006 13:45
            There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.
            <ymca-server.ymca-gwc.local #5.5.0 smtp;550 Open relay not allowed>

I have checked the relay settings and all appear normal.  I have tried recreating the default SMTP Virtual Server to no avail.  

I get the following error messages in the event logs:

Event Type:      Error
Event Source:      MSExchangeTransport
Event Category:      SMTP Protocol
Event ID:      7004
Date:            06/11/2006
Time:            13:28:57
User:            N/A
Computer:      YMCA-SERVER
This is an SMTP protocol error log for virtual server ID 1, connection #7. The remote host "", responded to the SMTP command "rcpt" with "550 Open relay not allowed  ". The full command sent was "RCPT TO:<stephen.gillham@fos.net>  ".  This will probably cause the connection to fail.

For more information, click http://www.microsoft.com/contentredirect.asp.


Event Type:      Warning
Event Source:      MSExchangeTransport
Event Category:      NDR
Event ID:      3022
Date:            06/11/2006
Time:            13:28:58
User:            N/A
Computer:      YMCA-SERVER
A non-delivery report with a status code of 5.5.0 was generated for recipient rfc822;stephen.gillham@fos.net (Message-ID <F6632B2AAF498F468A14172673FEB6B32DCE@ymca-server.ymca-gwc.local>).  
Cause:  This message indicates a generic protocol error (SMTP error).  For example, the remote SMTP responds to an issued EHLO with a 500 level error and the sending system will QUIT the connection and report this with NDR indicating the remote SMTP server canÆt handle the protocol.    
Solution:  View the SMTP log or run a netmon trace to see why the remote SMTP server rejects the protocol request.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Please help a.s.a.p


Watch Question

Expert of the Year 2007
Expert of the Year 2006

The party that you are sending to believes that you are an open relay. Have you checked to see whether that is the case?



as far as I am aware we are not, also this message does not appear to be leaving the server.  as we use an external Anti-SPAM solution I will check with them if they are blocking it and report back here.  


Our Spam guys report no issues (other than the lack of mail flowing through the service)

suggestions please?  I'm thinking of re-installing IIS and Exchange

Are you using Symantec AntiVirus Corporate Edition 9.0 on Exchange 2000 or Exchange Server 2003, and the Internet E-Mail Auto-Protect feature is enabled then this will happen.
By disabling the Internet E-Mail Auto-Protect feature of Symantec Antivirus Corporate Edition 9.X, messages can be delivered out.
Check this as well:

How to troubleshoot mail relay issues in Exchange Server 2003 and in Exchange 2000 Server

Expert of the Year 2007
Expert of the Year 2006
Not mimecast again.
That is the second time they have been involved with servers not sending email. They will very soon be on the list of companies to avoid.

Mimecast is reporting the problem, so you will have to ask them why they are rejecting the email.
I presume that you are sending your email out through their service as well as using them to screen inbound email?


Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts


yes we are, although I don't believe that it is really a MIMEcast issue as their  NDR's normally contain a notice to say that it came from them.  
Expert of the Year 2007
Expert of the Year 2006

Their server rejected the message:

The remote host "", responded to the SMTP command "rcpt"

Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.


Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.