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Why will Outlook Email not send message?

BKD82BKD82 Posts: 1 Newcomer
in Email May 05, 2023

Recently, Windows Live Mail client returns the error message below when trying to send message: As of 4/28/23, Sent folder shows messages sent. Now all messages are stuck in Outbox folder. Windows Live Mail 2011 on Windows 7 Pro.

The message could not be sent because the server rejected the sender's email address. The sender's email address was '[address deleted]'.

Subject 'Test'

Server Error: 550

Server Response: 550 5.1.0 <[email protected]> sender rejected. The email address you are sending as must match the email address you used to auth. Please check your SMTP settings. AUP#Out-1500

Server: ''

Windows Live Mail Error ID: 0x800CCC78

Protocol: SMTP

Port: 25

Secure(SSL): No

Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity.

Subject '-------------'

Server: ''

Windows Live Mail Error ID: 0x800CCC0F

Protocol: SMTP

Port: 25

Secure(SSL): No

Best Answer

  • William_MWilliam_M Posts: 606 Moderator
    edited May 5 May 05, 2023 Answer ✓

    Hi @BKD82, welcome to our community!

    The error you got means "Your email was rejected for attempting to send as a different email address than you signed in under. Check that you’re sending emails from the address you signed in with." It sounds like there is an issue with your Outlook configuration. Please make sure you have the correct email server settings entered. and that you are sending from your Spectrum email address. It can help to completely delete the outlook profile and then recreate it.

    I also highly recommend updating your Windows Operating System as Windows 7 is no longer supported by Microsoft and does not receive security patches, which makes that device extremely vulnerable if connected to the internet.

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