Verizon FIOS Blocking SMTP Port (Outgoing Email)

The Long Story…

I recently found out the hard way that the Verizon FIOS Internet Service Provider (ISP) has implemented port blocking for outgoing (SMTP) email to non-Verizon mail servers. I use a third-party POP3/SMTP mail server that comes with my web hosting account (I avoid using the free email accounts that come with ISP’s like Verizon to avoid changing my email address every time I switch Internet providers). Yesterday, I noticed that my Outlook 2007 was unable to send an email. It just sat in my outbox after repeated attempts to send-and-receive. I gave up and shut down my computer for the night assuming that a reboot would fix the problem.

This morning, I tried sending the same email with the same result. Outlook kept saying it was unable to access the outgoing SMTP mail server. I was able to download email via POP3 and I was able to access my webmail. So I tried sending email through one of my web applications which uses SMTP, and to my surprise, that worked fine.

I was starting to write an email to my web host complaining that they must have changed their SMTP authentication to block external IP addresses from sending email. Then it hit me – maybe my web host isn’t the one blocking traffic. The problem could be with Verizon. So I searched around a bit and found an announcement from Verizon that explained the whole thing. I changed my Outlook settings and now I’m back in business. I’m glad I didn’t send that angry support email to my web host. 🙂

Long Story Short…

Verizon FIOS is blocking outgoing (SMTP) email on Port 25. They’ve been rolling out this change since 2009 but apparently didn’t inform all of their customers. They say they’re doing it to reduce the spread of email viruses.

The “solution” is to change your SMTP port. Thankfully, many email providers (including mine) support Port 587 as an alternate SMTP port. Unfortunately, there will be some users who don’t have that option and are stuck not being able to send mail at all. Those unlucky folks will need to talk to their email provider or drop Verizon as their ISP.

If you’re having trouble sending mail using Verizon FIOS, check out the following links:

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10 thoughts on “Verizon FIOS Blocking SMTP Port (Outgoing Email)

  1. Larry says:

    I love you man….. I have not been able to send email for several weeks and could not figure it out… You are a life saver!

    Thanks again for taking the time to share!


  2. Chris says:

    Wow…. so I have only been able to send outgoing email while at work since I have FIOS at home. Its been months. Good lookin out, fixed me up within a minute of starting to read your post.

  3. Gary says:

    Thank you so much for posting this…. I was going crazy trying to figure this out… It’s working fine with Port 587.

    Peace, 🙂

  4. Iris says:

    My husband has apparently been “looking into this” for me for a month now. I finally just googled it and found your post. Thank you SO much! Not being able to send email from home was ridiculous!

  5. Kelly says:

    Why do these “internet engineers” believe this will work? The infections will use the client computers email client to send the emails, so they will still be sent since they are configured to use If they really want to stop all the malware/viruses/spam/botnets, why don’t they just block ALL the ports?

    They are a bunch of bumbling idiots. They have lost a customer for life. Again.

  6. I feel like I won a lottery after finding out I can actually send e mails from home. Thanks man. I wish you win a lottery so you can do work without pressure if you have any!

  7. John says:

    All of the above stole my thunder. When I changed the port to 587, the three emails sitting in my outbox for about three weeks now were gone in a flash. This was like music to my ears. Thanks so much for sharing this info. It was very kind of you.

  8. Marty says:

    It is July 2012 and this post is still awesome!!! I moved to Washington DC temporarily from Michigan and everyone here has Verizon FIOS. And like you, I am keeping my wideopenwest (wowway) email account. Just brought my desktop with me with all the email history. I could not send anything for many days. 587 port is the one that worked. Other sites listed different ones. You are a lifesaver and thanks a million for taking me from, mad as heck for the past 4 days, to “All Good”. All the best, Marty

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