How to check if port 25 is blocked?

To check if your Internet Service Provider (ISP), firewall or similar software is blocking port 25, you should do the following:

• Checking port 25 in Windows OS:

Open the start menu -> run -> type cmd and hit enter. In the windows command prompt type:

telnet yourdomain.com 25

*Note that telnet client may be disabled by default, so you will need to enable it.

• Checking port 25 in MAC OS:

Each MAC computer comes with a preinstalled terminal to execute command lines. Usually the terminal is located in the application folder -> Utilities -> Terminal.  Type the following code there:

telnet yourdomain.com 25

• Checking port 25 in Linux OS

Open your terminal application and type:

telnet yourdomain.com 25

You should see the following lines if it is not blocked:

220-site.webhostface.com ESMTP Exim 4.80.1 #2 Wed, 17 Jul 2013 06:56:22 -0500

220-We do not authorize the use of this system to transport unsolicited,

220 and/or bulk e-mail.

If it is blocked, you will just see: Connecting to YourDomain.com… and it will fail after a while.

In case the connection is blocked and your ISP provider is not able to unblock port 25, you can always use the alternative port: 2525.