Receive Connector on Exchange 2010 Std.

Hi Folks,

I have an Exchange Server 2010 std. edition. It was all working fine for almost 10 months and suddenly what happened is, any mails coming from outside was rejected

The sender receives the following message:
Delivery has failed to these recipients or groups:
'User Name ('
Your message wasn't delivered due to a permission or security issue. It may have been rejected by a moderator, the address may only accept e-mail from certain senders, or another restriction may be preventing delivery.
The following organization rejected your message:
Diagnostic information for administrators:
Generating server: #550 5.7.1 Recipient not authorized, your IP has been found on a block list ##

No changes been made to the receive connector except for the permission groups which has all the options checked except Partners. This change was done after the installation of the exchange on the default receive connectors.

Since I was not receiving emails, I did checked my firewall, spam suite and nothing seems to have problem, as I continue to have the problem even after disabling the spam suite.
Finally, I created a new custom receive connector, set the IP address as local IP with port 25. Checked only the Externally Secured (IPSec) option under the authentication and permission group as default, by this I started getting emails, but the sad part is, I get to lots of spammers in the mail queue and looks really ugly. When the newly created connector is disabled, removing the spam domains in the queue, it looks fine but unable to receive mails and again when enabled, all goes for six...

I have another domain in my office with exchange 2010, I copied the same settings for the receive connectors (on the default ones created during exchange installation), but doesn't work. Works only when I enable the new connector.

Your resolution is highly appreciated.

Who is Participating?
SurajConnect With a Mentor Commented:
Instead of using a relay connector. try adding the IP in the IP allow list. once done restart transport and then test.
Have you installed any Windows OS or Exchange updates recently?
jaihoAuthor Commented:
@x-sam: Tried that, no mails coming + no bounce error mail coming for the sender

@compdigit44: It happened on 8th March 2012, during that time, there was no windows / Exchange updates except for Windows Defender.
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compdigit44Connect With a Mentor Commented:
I like to work with the mind set what changed from the time something work until it stopped working. You stated nothing has changed hardware wise and not Windows OS or Exchange updates were installed. Did you try to removed the latest Windows Deferener updates or disable windows defender as a test?
Please upload the agent.log. for me.
Also please tell me what have you configured on ip block list provider agent?

I suspect some thing miss-configured on BlockListProvider Agent.
Meanwhile, as for a quick troubleshooting step try  to disable IP block list providers , restart transport and then test.
Have you checked the following:

-Open the Exchange Management Console.
  -Expand Server Configuration and select Hub Transport.
  -Right click on Default <Server Name> and select Properties.
-Click on Permission Groups.
 -Ensure Anonymous Users is checked and click Apply and then OK.
- Restart the Microsoft Exchange Transport service.
jaihoAuthor Commented:
@x-sam: Added the neccessary IP address in the IP allow list for spam

@compdigit44: Disabled the Win Defender

- Worked like charm... Thanks so much techies. Happy to learn a lot on this... :)
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