Forum Discussion

coxfiberuser-ph's avatar
coxfiberuser-ph
New Contributor
5 years ago

AUP#CXSNDR error when sending email

I am a Cox Gigablast user in Phoenix, AZ.  Since Wednesday, May 20, 2020, I am no longer able to send email from Mozilla Thunderbird using a third party email (xxxxxxxxxxx@media.mit.edu).  This has been working for many years and I didn't make any software changes recently.  I also have all the latest versions and patches of Windows and Thunderbird installed.
The error I am getting in a popup after I send the email is

An error occurred while sending mail. The mail server responded:  <xxxxxxxxxxx@media.mit.edu> sender rejected. Refer to Error Codes section at www.cox.com/.../email-error-codes.html for more information. AUP#CXSNDR. Please check the message and try again.

I am using the following SMTP config:   smtp.cox.net   port 465   Normal Password    SSL/TLS

CXSNDR
  • ChrisL's avatar
    ChrisL
    Former Moderator
    5 years ago
    This error indicates that the origin email system may not have an SPF record configured to allow our SMTP server to send email using their domain name. If they offer secure SMTP connections you may want to try configuring your email client to use their outbound server to see if that helps.

    -Chris
    • jredwolf's avatar
      jredwolf
      New Contributor
      9 months ago

      what does this mean?  I have sent similar messages to the same address list for years.

      what is a spf record?  It's all cox; via thunderbird. 

      • ColleenD's avatar
        ColleenD
        Moderator
        9 months ago

        jredwolf I'm sorry to hear you are having trouble. Are you seeing the CXSNDR error when sending with your Cox email address? If so, please email us at cox.help@cox.com with your name, address, description of the problem and a link to your  forum post. If you are having trouble with an email address from another domain, I recommend reaching out to the provider of that email address for assistance. 

  • jonjon34t's avatar
    jonjon34t
    New Contributor
    5 years ago

    I am having the same email sending issue and error message that also started about 5 days ago, in Orange County, CA.  Apparently, COX recently made it so you can't send emails using non cox.net email addresses. Grrrr.

    • LisaH's avatar
      LisaH
      Moderator
      5 years ago
      Hi Jonjon34t. In order to send an email from a Cox email server, you need to use a cox email account. - Lisa, Cox Support Forums Moderator