Windows Live Mail. Error code 0x800CCC78

I can now recieve but cannot send. Here is error code:


The message could not be sent because the server rejected the sender's email address. The sender's email address was *** Email address is removed for privacy ***'.

Subject 'Alan Lathrop 2 for 1'
Server Error: 550
Server Response: 550 5.7.1 Authentication Required
Server: ''
Windows Live Mail Error ID: 0x800CCC78
Protocol: SMTP
Port: 465
Secure(SSL): Yes


Original title: windows live mail


Question Info

Last updated June 16, 2019 Views 2,565 Applies to:

Hello Mr Fritz,


Welcome to Microsoft Community Forum. I will be assisting you on your inquiry about the error code 0x800CCC78.


There can be two causes why you're receiving this error code. It could be:


1. Incorrect POP settings (usually the SSL option for SMTP)

2. Firewall blocking ports


To troubleshoot the issue, please reconfigure your account by following the steps below:

  1. Access your Windows Live Mail program and check if there are emails stuck in the outbox. If yes, please delete those emails. (Note that you may need to go offline to do this part.)
  2. Remove and re-configure your account by following the steps within this link.

For the firewall issue, you can try to disable the security software/ firewall to isolate the issue. Please refer to the link below:


How can I resolve machine configuration issues in Windows Live Mail?


Let us know the results afterwards.


Thank you.

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