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BobW1's avatar
New Contributor
3 years ago

Sending EMail Issues

I get the following error when trying to send emails from Outlook:

Sending' reported error (0x800CCC6F) : 'Your outgoing (SMTP) email server has reported an internal error.
If you continue to receive this message, contact your server administrator or Internet service provider (ISP).
The server responded: 554 cmsmtp blocked.
Refer to Error Codes section at for more information.

I can send email's fine from Cox Webmail.

Any suggestions?

Outlook version: 

Microsoft® Outlook® for Microsoft 365 MSO (16.0.14228.20200) 64-bit

1 Reply

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  • Bruce's avatar
    Honored Contributor III

    0x800CCC6F is an issue with secure ports.  If you've changed absolutely nothing on Outlook (updates, add-ons, settings, etc), it's most likely an issue with the server.

    How many addressees on the email you're sending?  Do you send a lot of email to these addressees?  Could one assume you're spamming these addresses?