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I need Cox to Un-Block my company's email domain

I work for a small SAS software company that services mostly construction companies.

Our clients have the ability, through our software, to send individual and/or bulk emails to their clients. This is NOT spam email and are not sales related emails.

We do have a email sync program that, if a user saves their email provider, address and password in our system, allows their outgoing emails to be sent from the users actual email domain.

The problem is, if they do not have a email profile saved, and they send email out of our system - the emails come from our domain and are getting blocked 100% by Cox. We found this out recently as a client sent warranty specific email reminders out of the system. They verified that all of their clients received the email EXCEPT Cox customers.

We have run tests through our system and Cox is blocking 100% of our emails.

Simple, what do I need to do to have my domain removed from the "master blocked list" or whatever it is termed?

Please help, this is affecting our clients in a bad way and is reflecting poorly for Cox from a customer service standpoint.

  • @Jeff DBX

    If you're an outside email provider and sending to Cox but being flagged for spam you'll want to ensure that your email meet our guidelines listed at You may wish to consult with your mail admin for further assistance with the topics discussed there.

  • Thanks Chris

    Technically is not even making to the spam filters - Our mail is getting blocked prior to that protection.

  • @Jeff DBX

    Perhaps I'm not understanding your setup. Are you sending out from a Cox Internet connection or into email accounts?

  • Chris,

    Maybe I can explain better - sorry.

    I happen to be a cox subscriber and have an account (this one).

    I also work for a SAS software company ( that uses an email server ( tied to our system that our clients use to communicate with their customer base.

    Recently, Cox started blocking emails from my company's email server ( prior to any individual spam filters. I happen to know this because I also personally happen to be a customer for one of's clients and I stopped getting emails from them.

    This is how I found out that the emails were getting blocked.

    My huge concern is that we are NOT blacklisted in any RBL list, yet cox (only provider that we are aware of) is blocking us.

    We checked our server stmp logs and indeed verified that cox is blocking our emails - This note is from one of my developers:

    Jeff, I was able to check the smtp logs on the server and cox is indeed blocking the emails... I found this page: where the cox postmaster error codes can be checked. We're getting the IPBL1000 code which says the following: "The Sending IP is listed in the Cloudmark CSI DNSBL". I checked here: and according to this site we're not being listed in any RBL list so I'm not sure what's going on.

    Are you able to assist me with this or is there a way for me to open an official ticket?

    Any help is greatly appreciated.

  • @Jeff DBX

    That being the case my original reply would be accurate. Your email provider should visit to determine what needs to be done to make these emails compliant with our spam control policies.