• FPO ImageContact Us
  • Select a Location
    Select a Location

    Current Location:

    Let us know the location you'd like to browse.



Having problems with your Internet Connection? Did you know that most Internet connectivity issues can be solved by using our Modem Reset tool? Just sign-in, click the Reset button, and get back browsing the Web. >> Reset My Modem

Back Print Article

Unsolicited Email Spam Information

Last Updated: Tue, 15 Sep 2015 > Related Articles

56 rated this


Learn more about how Cox manages unwanted spam and ways you can help.


No one likes receiving unsolicited email spam. The increase in spam is causing legitimate Internet users and Internet service providers, such as Cox Communications, to spend a great deal of time, money, and good will addressing the problem. In addition, several state legislatures and Congress are trying to stop spamming through legislation.

Cox does not provide its customers’ email addresses to spammers and does not permit its customers to send unsolicited mass emails. Cox’s Acceptable Use Policy (AUP) expressly prohibits the use of Cox High Speed Internet to generate spam. The accounts of customers who violate Cox’s anti-spam policy may be suspended or terminated.

Cox has a variety of measures in place to help protect our Cox High Speed Internet customers and our network from spam, and we continue to look for ways to improve our services through the control and elimination of spam. Learn more about controlling spam using the information below.

Reducing Incoming Spam 

There are things you can do to understand the problem and help solve it. Following these tips can help reduce the amount of email spam you receive.

  • If you post to newsgroups or message boards, you can change your email address by adding spaces or characters to deter spammers from harvesting it. If your email address is in your email signature, you can remove it or use the same technique.
  • You can also remove your name from major online directories.
  • You should never respond to an unsubscribe link in any unsolicited email. Doing so can prompt even more mail from the source.
  • If you receive an unsolicited commercial email, you may report it to the sender’s ISP. To do this, you must view the spam email's complete message header to identify the source network, and then send a report to the network’s administrator.

Cox identifies addresses of known spammers to add them to our black lists. This is one step in our investigation of network-based anti-spam solutions that integrate with our email platform. It allows us to recognize and block spam from known spammers using both rules-based methods and white or black lists.

Controlling Outgoing Spam 

To reduce unsolicited bulk email sent on our network, Cox uses outbound SMTP traffic filtering, which is also known as port 25 filtering. Cox also filters all inbound SMTP traffic to help protect unsecured computers from being used as spam mail relays.

  • Outbound SMTP traffic blocking protects Internet users and the Cox High Speed Internet network. The vast majority of customers are not affected by this security measure. However, a small number of customers using email addresses outside of the @cox.net domain and do not have their SMTP servers set for Cox mail servers need to change their settings. The requirement that Cox servers be used for all outgoing mail is so that Cox can locate and control spammers by removing them from the network.
  • Outbound SMTP traffic blocking is an industry standard. Other ISPs blocking port 25 include Charter, Comcast, MSN, and Verizon. You can search the Internet for a complete list of ISPs blocking port 25.
  • Since implementing port 25 blocking, Cox has seen significant reductions of residential Internet abuse reports. Reports for port scanning decreased by 36%, viruses by 41%, spam by 52%, and open proxy by more than 78%.

Frequently Asked Questions 

I’m getting spam even though I have never given out my address. Is Cox selling my information?

We do not sell our customers’ email addresses. Sometimes spammers will try lists of common names or words in different combinations to locate an active email address. For more information, review our Privacy Policy.

How can I prevent spammers from getting my email address?

Avoid placing your email address on websites or newsgroups. When providing your email address to third parties, verify their privacy policy to determine if they sell your information and what you can do to prevent it. Only provide your email address to trusted parties.

Does Cox Communications sell or give my email address to third parties?

Read our complete Privacy Policy.

What ports does Cox currently block or filter?

To see which ports Cox blocks or restricts see Ports Blocked or Restricted by Cox High Speed Internet.

Does Cox block or filter port 25?

Yes, Cox blocks all network traffic from residential customer IP addresses going outbound on port 25 (SMTP) at our routers, unless it is being sent to a Cox High Speed Internet SMTP server.

Does the outbound blocking of port 25 mean that Cox customers have to use their @cox.net email addresses for everything they send?

No. Customers can use any valid email address, but the email sent from their Cox High Speed Internet connection must be routed through a Cox SMTP server.

What are the correct SMTP server settings to use on the Cox High Speed Internet Service?

For more information on setting up email, refer to Email Server Names.

Why does Cox block outgoing mail from use of port 25?

The filter of port 25 drastically reduces the number of spam and virus emails originating from our customers' computers. Cox had to take this action in order to ensure that a few bulk emailers and virus disseminators did not result in the entire Cox.net domain being blacklisted by other Internet Service Providers.

Other ISPs don’t block outbound use of port 25, why does Cox?

Although some ISPs may currently allow the use of third party outgoing mail servers, other providers do block outbound use of port 25. We adopted this industry standard to help control the volume of outgoing spam and the dissemination of viruses. As the problem of spam continues to proliferate, we believe that other ISPs will implement this and similar blocks.

How does the filter of port 25 help with the problem of spam?

Typically, when a customer sends an email, it is routed to a cox.net mail server, such as smtp.cox.net, and the Cox server relays it to the recipient’s server. Spammers and modern mass mailer viruses commonly bypass the cox.net mail servers. They send mail directly from their computer to others’ mail servers without routing it through a cox.net mail server. The filter of port 25 prevents spammers from bypassing cox.net mail servers and delivering spam directly to Internet users. Also, this filter prevents viruses from propagating at all.

Does the filter of port 25 hinder customers’ ability to send email?

The filter of port 25 does not impact the vast majority of Cox customers, only a small percentage of customers who use third party mail servers. Any software configured to use an SMTP server other than smtp.cox.net to deliver email directly to a recipient's server will not work. An indication of this problem may be a message similar to this in the customer’s mail client.

"A time-out occurred while communicating with the server. Account: ‘otheraccount.othersisp.com’, Server: ‘othersmtp.com’, Protocol: SMTP, Port 25, Secure (SSL): No, error Number: 0x800CCC19."

Customers using third party email services must configure their email clients to use smtp.cox.net to send outbound email. Remember that operating an email or other server on a residential Cox High Speed Internet connection is a violation of our Acceptable Use Policy.

Some Cox customers use a laptop at both home and office. The port 25 filter forces some of these customers to change email settings when checking work email from home. What is Cox’s solution for this?

Many customers in this situation have been able to use a virtual private network (VPN) connection to access their email without having to change settings. Another solution may be using web-based email applications where applicable. A third option is to simply adjust the setting when working from home; this is typically a one-line entry within the email client on the computer.

Does the filter of port 25 affect web-based email services?

No. Customers may continue to use Cox High Speed Internet WebMail or services like Gmail and Yahoo mail as they always have.

Does the filtering of Port 25 outbound affect the receipt of inbound email?

No. This does not affect retrieval of inbound email from any service.

I pay for my own domain name so I can send personal email through that server. Is Cox blocking this legitimate use?

We understand that some customers have vanity domain names. Cox does not prevent customers from using their personal domain names. To ensure your ability to send email from your personal domain so that the recipient sees a non-cox.net email address in the From or Reply to address, your mail client must be set to a Cox outgoing mail server. The domain used in any such address must have an MX record that can be resolved by Cox DNS servers, such as mac.com, or yourdomain.com. These settings are transparent to email recipients and will not impact your ability to receive email. If you have a business requirement to bypass the Cox mail servers, contact Cox Business Services for additional options.

Does Cox read my email?

No. We respect your privacy and do not read any email messages, instant messages, online chats, or the content of other online communications that reside on or pass through our service. If you would like more detailed information, see our Privacy Policy.

What is the CAN-Spam Act?

The CAN-Spam Act, was effective beginning on January 1, 2004. It preempts all state spam statutes and places a series of requirements on commercial email, “the primary purpose of which is the commercial advertisement or promotion of a commercial product or service.” This act requires companies that send or initiate commercial email to do the following.

  • Refrain from using a misleading subject heading
  • Provide in each message a valid return email or Internet-based reply address
  • Provide in each message a physical postal address in the text
  • Provide a conspicuous notice that it is an advertisement or solicitation
  • Include a notice explaining how recipients can prevent the transmission of future messages by using the sender’s return email address or Internet-based reply address and honoring such requests within 10 days
  • Refrain from selling or exchanging the email address of any recipient who has made an opt-out request

Businesses are permitted to send “transactional or relationship messages to facilitate, complete, or confirm a commercial transaction that the recipient has previously agreed to enter into.” This is intended to be a very narrow exception and would include warranty, recall, safety, or security information regarding a product previously purchased, periodic account statements and the like. “Transactional or relationship” messages may also contain content promoting a product or service unrelated to a previous transaction if ancillary to the primary purpose of the communication.

A safe harbor exists for companies that have reasonable compliance practices and make good faith compliance efforts. The Act also requires the FTC to study the creation of a nationwide Do Not Email registry similar to its Do Not Call list.

How does the CAN-Spam Act impact Cox High Speed Internet customers?

It is widely recognized that government efforts to prevent spam will be difficult. Early legislation on this issue by various states and nations has been criticized as being difficult to enforce and police. Many spammers are very crafty in their techniques which make them difficult to trace. Nevertheless, Cox supports federal efforts to establish laws such as the CAN-Spam Act, which includes penalties for spammers. Cox also looks forward to the advent of policing methods and technologies that will reduce unwanted email that is a nuisance to customers and costly to their productivity. Cox High Speed Internet customers are already prohibited from sending spam in the Cox Acceptable Use Policy.

Rate this Article:

Related Topics:

Give us your feedback:


Maximum 500 characters

Back Print Article