eMail,  Outlook,  Troubleshooting

How To Fix Your Port Settings If Cannot Send Mail From Outlook

Almost all mail client program send e-mail using port 25, which is also the port used by mail servers to talk to each other. But port 25 is widely abused by malware to spread worms and spam. As a result, many ISPs are restricting its use.

Hang on – it will make sense in a second:

Most people having a setup where they are on an Internet Service Provider (ISP) like ATT and have an email address like “”  You connect to the internet using ATT and send mail through the ATT server – no problem.

But if you have your own domain email address or an email address from another ISP you may hit a snag. In these cases you are connecting to the internet through your ISP (like Comcast, SpeakEasy, ATT, etc) and trying to send email through your third party host like “”

Your ISP says “Hey! There is someone on my network trying to send email through someone elses address! This might be spam or malware!” You can receive mail, but you can’t send mail.

Recently ATT and Verizon both made changes that affected outgoing mail. Here’s the fix:

If you cannot SEND MAIL

  1. Open OUTLOOK
  2. Select TOOLS
  4. Highlight the account in question and select CHANGE
  6. Select ADVANCED
  7. Change from PORT 25 to PORT 587
  8. Save everything and restart Outlook


Other email programs will have similar settings. Look for PROPERTIES or PREFERENCES and find the outgoing mail server option.

One other option to check is that you are authenticating before sending. In other words. logging in with your username and password to both check and send email.

In Outlook the options window looks like this:


This tells Outlook to send your username and password before trying to send mail. If you have problems try enabling or disabling this setting.

The screen shots used in this how-to are my actual settings and they work just fine with SpeakEasy and ATT.


  • Linda

    I spent two hours on phone with AT&T they tried to sell me a business package to open port 25. i found this after researching hours on the internet. Changed port to 587 and all is fine. No one at AT&T could help me. I was beyond mad since all I had done was move my office and instead of having DSL they chnaged me to u-verse and insisted everything would be the same What a pain in the A__!!!

  • Ramesh Ramakrishna

    very very good solution.
    Highly Appreciate your help to the dump users like me.
    I could fix this problem with in 5 min, for which I looked around every comp. engg and broadband service support people for 4~5days…
    excellent work you are doing Mr. Daniel Curran

  • Tress

    HELP! I just switched to Uverse. I tried following your screen shots but my options look different. There isn’t a place to change those things. Even when I clicked “Advanced”. I have Outlook 2011 on my Mac. There are not near the options as are shown on your screen shots. I’ve read other forums as well and yours seems to be my best chance.

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