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504 5.7.4 Unrecognized authentication type in Protocol Logs\SMTP Receive

    Question

  • I have Exchange server 2010. In Protocol Logs\SMTPReceive on Edge server I see message '504 5.7.4 Unrecognized authentication type' from one IP address. let say that in few minutes I have 400-500 this messages from that IP only different port is used.

    My question is: how can I block this IP from even attempting to authenticate?

    I know for IP Block List, but when I enetr this IP address in the block list, it doesnt block IP from authenticate.

    Tuesday, October 20, 2015 5:11 AM

Answers

  • You could block it in the Windows Firewall or your hardware firewall. 

    You might try creating a new receive connector with that IP address in RemoteIPRanges, and AuthMechanism set to None.  I haven't had any need to do this, so it's just a prototype idea and you'd need to test it.


    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!


    Tuesday, October 20, 2015 6:24 AM
    Moderator
  • Hi,

    Please refer to Ed's response to have a test.

    You can have a look at the below article to configure the receive connector:

    https://technet.microsoft.com/en-us/library/bb690954(v=exchg.141).aspx

    Regards,

    David 

    • Marked as answer by bckms Wednesday, February 24, 2016 5:40 PM
    Wednesday, October 21, 2015 2:28 AM
    Moderator

All replies

  • You could block it in the Windows Firewall or your hardware firewall. 

    You might try creating a new receive connector with that IP address in RemoteIPRanges, and AuthMechanism set to None.  I haven't had any need to do this, so it's just a prototype idea and you'd need to test it.


    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!


    Tuesday, October 20, 2015 6:24 AM
    Moderator
  • Hi,

    Please refer to Ed's response to have a test.

    You can have a look at the below article to configure the receive connector:

    https://technet.microsoft.com/en-us/library/bb690954(v=exchg.141).aspx

    Regards,

    David 

    • Marked as answer by bckms Wednesday, February 24, 2016 5:40 PM
    Wednesday, October 21, 2015 2:28 AM
    Moderator
  • OK, I will make a test.

    First I'm testing over windows firewall, a than Receive connector. I need some time.

    I will inform you.

    Wednesday, October 21, 2015 8:34 AM
  • I created another Receive Connector (beside my default receive connector), with "IP address in RemoteIPRanges, and AuthMechanism set to None".

    But I receive email from that IP address that I wanted to block.


    • Edited by bckms Thursday, October 29, 2015 11:31 AM
    Thursday, October 29, 2015 11:31 AM