1. Knowledge Base
  2. >
  3. Results
  4. >
  5. Are you able to receive emails but not send?

Are you able to receive emails but not send?

By default, your email is typically set on port 25 for outgoing mail - the channel used for communication between an email client and the server. But some internet service providers (ISPs) block port 25. If your ISP is blocking port 25, your messages will not get through. 

If your ISP is on the list below, you will need to change the outgoing mail server (SMTP) to port 26 or port 587.

If you use Outlook, please be sure to select the option for Outgoing SMTP Server Requires Authentication. This is now required for our server security.

Some ISPs that block port 25 include:

  • AT&T
  • MindSpring
  • BellSouth
  • MSN
  • CableOne
  • NetZero
  • Charter
  • mails
  • People PC
  • Comcast ATTBI
  • Sprynet
  • Cox
  • Sympatico.ca
  • EarthLink
  • Verio
  • Flashnet
  • Verizon
  • MediaOne
  • Telus

How to Change Your Outgoing Email Port

If your ISP is on this list or you believe port 25 is blocked, you will need to reconfigure the account for your email client to change the outgoing SMTP port from 25 to 26 or 587. Check the following articles for information and assistance with common email clients for Mac, Windows or Mobile:

What If Both Port 25, Port 26 and Port 587 Don't Work?

You will need to follow your ISP's procedures for outgoing email.  

Contact your ISP to request either: 

  1. They open one of these ports for you; or
  2. Information for the correct SMTP server you should be using.

Some ISPs may require you to use their SMTP servers for all outgoing mail so that they can monitor outgoing email on their network in order to prevent spam.

This information is usually posted on a page of their website.  If they have a search box on their site, searching for "port 25" will usually lead you to the relevant information. 

Note: For Comcast/Xfinity Internet customers, port 587 is available for use as ports 25 and 26 are blocked on their network.

My Mail Used to Work

Sometimes ISPs change their policies and start implementing blocks to certain ports without informing their customers (other than perhaps a post on their website). Most ISPs post information about Port 25 on their website if they have implemented a policy of blocking it. If sending mail suddenly stops working, this is probably why.