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Outlook send produces error "The email address you are sending as must match the email address you used to auth. Please check your SMTP settings. "

Anonymous
2023-05-25T12:28:02+00:00

Using Outlook 2019, Windows 11, and MS Office Professional 2019, my Outlook send produces error "The email address you are sending as must match the email address you used to auth. Please check your SMTP settings. AUP#Out-1500'". However, emails are being successfully sent. How do I get rid of this invalid error?

I have removed and re-added my IMAP email account (server is mail.twc.com). I checked with Spectrum to verify account settings. Receive and send are both working but I get this error every time I send an email even though the email is sent. It is like there is some phantom email trying to be sent.

I have 3 email accounts that are synchronized in Outlook, 2 gmail accounts and 1 IMAP account. The IMAP account is the one producing the error.

I tried deleting the roaming cache.

Each time I open Outlook, the Send/Receive action occurs (which is correct behavior), but Outlook seems to be trying to send an actual email that doesn't exist and throws this error. Then when I send an actual email, that email is sent but the error still occurs.

I tried uploading a screenshot but each upload attempt fails.

The error is:

Task 'Mark_PC - Sending' reported error (0x800CCC0F) : 'The connection to the server was interrupted. If this problem continues, contact your server administrator or Internet service provider (ISP). The server responded: 550 5.1.0 <> 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'

Outlook | Windows | Classic Outlook for Windows | For business

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  1. Anonymous
    2023-08-21T19:32:29+00:00

    I also had this issue with Spectrum email and Outlook 2013. I could receive, but not send emails through Outlook. I was able to send them from my account through Webmail. After reading that there didn't appear to be a solution (I never give up!), I looked into my Outlook account settings and selected Change and then selected More Settings. I selected the Outgoing Server tab and checked "My outgoing server requires authentication" and also completed User Name, Password and checked the Remember Password box. Now Outlook works fine! Hope this helps.

    20+ people found this answer helpful.
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  2. Anonymous
    2023-09-21T15:10:11+00:00

    I got the same error message from Spectrum using eM Client instead of Outlook on two computers. Nothing has changed software-wise on my end, so I assumed Spectrum caused the problem. Spectrum support was no help as usual, even claiming that I should contact eM Client because SMTP sent outgoing e-mail to them and they forwarded it Spectrum (what!!).

    After a little research on how SMTP worked and some experimentation, I fixed the problem by changing the eM Client SMTP Authentication settings from none (“Server requires authentication” box unchecked) to

    "Server requires authentication” box checked

    "Use these credentials" box checked

    User name: <my full Roadrunner email address>

    Password: <my Roadrunner password>

    It appears that Spectrum changed the smtp-server site authentication code, but left the pop-server site alone so that received e-mail was unaffected. As a wild guess, it may have had something to do with my POP3 Authentication "Use these identity credentials" having a User name of <name> rather than my full e-mail address of <name>.cfl.rr.com. Perhaps the updated SMTP code no longer treats <name> as a shortcut for <name>.cfl.rr.com.

    10+ people found this answer helpful.
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  3. Anonymous
    2023-09-29T18:29:59+00:00

    George L. I just came across your post today Sept 29 3023. I have Outlook 2010 which I have been using all along on my desktop computers and now my laptop computer. On or about September 24 something happened where I was unable to send messages. Any messages that I created went to Outlook 'Outbox which never has happened before all these years/decade with MS Windows versions throughout time. I have always had POP3 settings and everything worked fine. My internet provider is Spectrum. I believe George you are totally correct that Spectrum did change something but failed to let their customers know about any change in POP3 Authentication/SMTP. I opened Outlook 2010 went into Account settings, More settings (Internet e-mail settings). Under "Outgoing Server", I unchecked 'Use the same settings as my incoming mail server which then populated to enter information "Log in using" circle checked now. I entered my full Spectrum email address (not just name like you said), I entered my password the same password used for Spectrum webmail, "My outgoing server (SMTP) requires authentication" was already checked, the "Remember password" box was already checked, 'Requires SPA not checked, by default I guess, "Log into server before sending mail" was not checked. I then clicked on OK and Outlook 2010 began doing "Testing account settings" and Outlook window said log in and sent message test was successful. A change Account window popped up (this is Outlook 2010 "Change Account wizard and it said, Congratulation! all set. S. C/S is useless and overpriced greed.

    ![Image](https://learn-attachment.microsoft.com/api/attachments/9fc9be19-82a9-4e03-8700-0bac713d0a46?platform=QnA

  4. Anonymous
    2023-09-29T19:15:41+00:00

    I had the exact same error, "The email address you are sending as must match the email address you used to auth. Please check your SMTP settings. AUP#Out-1500'".

    For some reason Spectrum (Charter) etc. changed something which I started have problems sending emails September 24, 2023. What I believe is Spectrum (Charter) changed something on their end for outgoing 'sent email in settings (SMTP) but never informed customers of the change. Fact is now what I found is that you can no longer use the same 'incoming settings for outgoing SMTP settings (box that is checked or unchecked). I have Outlook 2010 decades now without problems on both desktop pc and now laptop pc always been POP3 and still is. In Outlook 2010 account settings, I unchecked: 'Use same settings as my incoming mail server', then procced to: Enter full email address, entered same password used for web mail, Remember password was pre-checked, My outgoing server (SMTP) requires authentication was pre-checked. Now Outlook 2010 is sending mail fine. I even got an email from Outlook after successful 'wizard set up told me Congratulations. I am here Friday September 29, 2023 at 3:13 PM. Hope this may help some. For some who may think they want to consider a fix and switch to IMAP from POP3 be careful I read once you create new IMAP you may lose your POP3 email data, your emails and more.