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Connection dropped due to socket error RRS feed

  • Question

  • Hi

    I have exchange server 2016 with CU11 at home on Windows 2012 R2 and server is receiving mail Ok on port 25.

    However since it is at home I try to use smart host with my internet provider and they gave me smtp smart host name and since it is residential they dont allow port 25 but they told me to use 465 Incoming mail is still coming on 25 however outgoing mail will  not. This is residential line  so IP is not always the same.

    This used to work all good until i upgraded to about Cumulative update 9 after that it all stopped working with error below

    I have setup smart host and provided user name and password with TLS authentication on port 465 but messages are stuck in queue with error

    LED 451.4.4.397 error communicating with target host 421.4.4.2 Connection dropped due to SocketError.

    So I have decided to try routing this mail via G Suite domain as routing host however i am getting same message all the time.

    This led me to conclusion that something is not working with my Exchange Server.

    I have MX records in Go Daddy as well as SPF and mail was flowing OK. I suspected something on provider however now after trying Gsuite domain smart host as well then definitely something either with exchange or other settings

    This is Lab server so i just wanted to send limited number of messages.

    Have checked with MX Toolbox if my mail is blacklisted but it is not

    Send connector is setup to send on 465 and I am able to telnet smtp relay host on that port.

    Exchange server is connected to Cisco ASA 5505 router and internet is working 


    Dalibor Bosic



    • Edited by cer113 Sunday, October 28, 2018 1:05 PM
    Sunday, October 28, 2018 1:01 PM

All replies

  • Hi,

    How do you configure the send connector to send on port 465?

    Here is a blog for your reference, you may get some useful information: Exchange 2013/2010 – 421 4.4.2 Connection dropped due to SocketError
    Note: Microsoft is providing this information as a convenience to you. The sites are not controlled by Microsoft. Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please make sure that you completely understand the risk before retrieving any suggestions from the above link.

    Regards,

    Lydia Zhou


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

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    Monday, October 29, 2018 10:51 AM
  • Here is how it is configured

    Give send connector name

    send connector is sending mail on 465 confirmed

    under smart host name is smtp.broadband.provider.com

    then user name and password given by ISP

    offer basic authenticatioin only after starting TLS

    Scoping  domain is * and cost 1 and source server is my exchange server

    Name                                                                                                               Port
    ----                                                                                                               ----
    Outbound to Office 365                                                                                               25
    Internet                                                                                                            465

    However same error over and over again

    Article that you gave me I have tried that too but error persists

    name of connector is Internet


    Dalibor Bosic


    • Edited by cer113 Monday, October 29, 2018 9:42 PM
    Monday, October 29, 2018 9:36 PM
  • Hi

    I have changed to port 587 and error is now different it now says Require TTLS to start basic authentication

    Says Target host responded Require STARTTLS to do basic authentication

    How would i Start TLS on exchange


    Dalibor Bosic


    • Edited by cer113 Monday, October 29, 2018 11:21 PM
    Monday, October 29, 2018 11:07 PM
  • Hi

    This is now resolved apparently to smart host with my provider I had to use 587 and then authenticate and it is working now


    Dalibor Bosic

    Tuesday, October 30, 2018 12:14 AM
  • Hi,

    If you don't mind, we'd suggest you mark the reply above as answer, so it will be easy for other community members to find the useful one. 

    Thanks for your understanding.

    Regards,

    Lydia Zhou


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Click here to learn more. Visit the dedicated forum to share, explore and talk to experts about Microsoft Teams.

    Tuesday, October 30, 2018 11:03 AM