Hi I have a exchange 2010 server with HT, CAS and MBX roles installed on a single server. My users are able to send emails to internal and external users but they are not able to receive emails from any external users. i have tested this by sending a test email from my hotmail account to internal id but received below error message. Reporting-MTA: dns;col0-omc2-s9.col0.hotmail.com Received-From-MTA: dns;COL104-DS22 Arrival-Date: Wed, 9 May 2012 08:18:21 -0700 Final-Recipient: rfc822;muhammad.faheem@corvit.com Action: failed Status: 5.3.0 Diagnostic-Code: smtp;553 5.3.0 Open spam relay - see http://www.sorbs.net/ Riaz Javed Butt MCITP Enterprise Administrator MCITP Enterprise Messaging Administrator

What is the history of this installation, has it worked previously? If so have any changes been made? Is there anything between the internet and your Exchanage server?

The NDR means what it says - SORBS is blocking the message. If you are using a blacklist provider on your server then you need to remove it. Simon. Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

The NDR means what it says - SORBS is blocking the message. If you are using a blacklist provider on your server then you need to remove it. Simon. Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Hi Simon I am not using any blacklist provider on my server. For Anti Spam we are using Build in feature of Microsoft Anti Spam. Can you please let me know how can i check blacklist provider on my server? so that i can checked wheather any other admin user in my organization has modified this or not. Thanks. There is nothing in between my exchange server and internet. Riaz Javed Butt MCITP Enterprise Administrator MCITP Enterprise Messaging Administrator

Hi Simon, I had run testexchangeconnectivity to check the connectivity of my exchange server but i found error or insufficient system storage but when i checked storage its 3.87 GB available storage. i had increased storage to 6 GB and disabled Blacklist provider and now users are receiving emails from external users. Issue is almost sort out but i am still not available to find out the root cause of this issue. Any help from your side would be highly appreciated. Thanks.Riaz Javed Butt MCITP Enterprise Administrator MCITP Enterprise Messaging Administrator

The root cause is what you have identified - the use of a blacklist and the lack of disk space causing transport to shut down. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

In the future you may want to look into monitoring mail routing, are you using anything to alert on this now?

Hi, How is the issue now?Xiu Zhang TechNet Community Support