Verizon to Block "Send eMail" SMTP Port 25


I arrived home the other day to find this message on my answering machine:

That’s right folks: Verizon is blocking port 25, the port used for sending email, on its network. I immediately went to their website to find out what I had to do to keep sending email.  Part of the page in question is at the bottom of this post.  It turned out that they wanted me to switch my mail sending port to 587.  No problem.  I did that, only to find that none of my email providers have that port open!  I got in touch with HostMonster support.  (They host Cosmic Things)  They told me to try port 26 because they don’t open port 587 on their network.  It works with all of my email services, but I hope Verizon isn’t planning on blocking Port 26 at the same time as 25,because then I’m in trouble.  How do you feel about Verizon blocking port 25?  Let me knowas a comment below the following excerpt.

Most common email viruses are sent using port 25 to infect computers. Often times the user never knows their computer has been infected. In order to protect our customers, Verizon has turned off the ability to send email using port 25 for all users other than those using a email address.

If you want immediate step-by-step instructions, visit change my port settings to 587 now.

What is outbound port 25 blocking?

Outbound port 25 blocking is a network configuration change that will prevent computers on the Verizon network from connecting to servers outside of our network. Servers outside the Verizon network use a method commonly employed to send unauthenticated, unsolicited e-mail or “spam”.

Why is Verizon blocking outbound port 25?

The majority of spam (unsolicited email) on the Internet is caused by malicious software viruses that take control of infected computers. These viruses direct the infected machines to send email through port 25. Verizon takes spam very seriously. Verizon blocks outgoing connections on port 25 to prevent infected computers from being used by spammers to send unsolicited email. Outbound port 25 blocking is a standard industry method to control spam.

Will outbound port 25 blocking apply to all Verizon broadband customers?

Outbound port 25 blocking will be applied to FIOS and High Speed Internet services that use dynamic IP addresses. If you subscribe to a static IP address service, you will not be affected.

Do I have a dynamic IP address?

If you have standard residential or business FIOS / High Speed Internet service, you have a dynamic IP address. Static IP packages are sold as an upgraded service.

Will I be impacted by port 25 blocking?

If you have a dynamic IP address and you use a third party email account to send email from a desktop client such as Outlook®, Outlook Express® or similar programs, you may be affected and should continue to read this notice. If you are using email provided as part of your VErizon service or a web-based email account from another provider, you will not be affected.

I am using a third party email account that I access using my web browser. Will I be affected?

No. Web-based email services will not be impacted.

I am using a third party email account. I also use a desktop client to manage my email. What must I do to continue using my third party service?

You have three options:

  1. Change your email client to send email using port 587. Click step-by-step instructions to change your port settings now.
  2. Use web based email services. Web based e-mail is unaffected by port 25 blocking. Check with your e-mail provider to see if web based access is available.
  3. Upgrade to a FIOS or High Speed Internet account with static IP addressing. Business customers may subscribe to static IP addressing.

About The Author

Jamie is a co-founder and senior editor at Technigrated, covering all facets of the tech industry. In addition to working at Technigrated, Jamie is a Founding Partner of NBR Design Studio, a graphic and web design and hosting firm headquartered in Bethany Beach, DE.


  1. The internet was built on standards and not on a whim. RFC 1651 states mail to be sent on Port 25. I was a verizon dsl customer and they never informed me of the change. They would not turn the port on so I canceled. I found out by my own diagnosis "telnet Mailserver.X.X 25 (specifying port 25). What happens when verizon turns off port 80 for mail surfing. A fact about Port 25 – it is the most widely used port on the public internet. Essentially they have turned off IETF standard service. Other companies have combated this by installing mail relays, or spam engine sniffers and will close individuals off if they are found to be abusing the service which is acceptable. To install an network trial and closing people down without prompting is not an option for long standing customers.

    Aside, they want me to pay early cancelation fees when they stopped providing service they promised.

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  5. Well, today was my turn to have port 25 blocked by VZ. I guess you should consider yourself lucky since you've got an advanced warning. I didn't. What really sucks about the situation is that I can get SMTP pass on neither port 26 nor 587. I have even tried an (almost) arbitrary port 2500 – still no go ( I support the SMTP server so I can make it listen on any port I want). I'm going to try ports above 5000 but in general, if they start shutting down arbitrary ports (5060 for example to eliminate VoIP competition), we are going to have to start rallying for Net Neutrality laws.

    • It's not right for them to go shutting off ports. I agree completely with you. I am all for net neutrality, but we will have to see what happens. I can imagine the headaches this is causing the less tech savvy people who don't even know what a "port" is.


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