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OldMainframeGuy's avatar
OldMainframeGuy
New Contributor III
6 years ago

CXSNDR error sending E-mail - is this permanently broken?

Since last night I have been receiving this error when trying to send E-mail:

An error occurred while sending mail. The mail server responded: 5.1.0 sender rejected. Refer to Error Codes section at www.cox.com/.../email-error-codes.html for more information. AUP#CXSNDR. Please verify that your email address is correct in your account settings and try again.

I use pobox.com as a spam filtering/mail forwarding service and this is set-up as my sender address in Thunderbird.

If I change my sender address to use the cox.net domain I can send e-mail but I don't want to use that address; I want to use the pobox.com address which has been working for many years. I called Cox tech support this morning and was unable to get a straight answer as to whether Cox recognizes this as something that's broken and needs to be fixed. Can anyone from Cox answer this please?

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  • KevinM2's avatar
    KevinM2
    Former Moderator
    6 years ago
    Hi OldMainframeGuy, we recommend updating your computer or other device operating systems and third-party applications to the latest versions, including security patches, email client programs (Thunderbird). -Kevin M. Cox Support Forum Moderator
    • OldMainframeGuy's avatar
      OldMainframeGuy
      New Contributor III
      6 years ago

      Kevin:  I'm running the latest release of Windows 10 with all current updates and the latest version of Thunderbird.  This looks to me (I could be wrong!) like an issue at your end where you are not accepting an E-mail sender address other than cox.net; many users were incurring the same error.   I had Thunderbird set to use the pobox.com domain for many years without issues.    As long as it's working now I'm OK.

  • enjay's avatar
    enjay
    New Contributor
    6 years ago

    Thanks to a suggestion in another thread, I unplugged PC, modem and router. I then powered everything back up. When I went into outlook, the emails stacked up in my inbox started sending. I am running Office Outlook 2016 and Win 10. I just wrote a new email and it sent immediately with no error messages. Good luck to all.