How to Verify Mail Client Settings Using Telnet

 

Checking usable ports with Telnet on Windows:

Note: Microsoft Windows does not come with Telnet enabled by default. If you are on Windows, please consult the following resource article to enable Telnet before proceeding:

Install Telnet Client.

Step 1: Open up the command prompt.

How to open command prompt:
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Windows 7/Vista/XP/98: Start > Run > type cmd > press Enter

Windows 8: Click the Windows icon in the lower-left and type cmd into the box. Hit enter or select cmd with your mouse.

Windows 10: Click the Windows icon in the lower-left and type cmd. Hit enter or select cmd with your mouse.

Shortcut: Hit Windows Key+r and type cmd then press enter.
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This is what you should now see:

Step 2: type "telnet yourdomain.com 465" then hit enter.

*Be sure to change yourdomain.com to the domain you are trying to send mail from. In this case, I will be connecting directly to a test server using its hostname.

You should see the following results:

This result indicates that port 465 is NOT blocked on the network, and you should have no issues configuring your mail client to connect over that port.

However, if you see the following:

Then your ISP is blocking port 465, and you will need to configure your mail client to connect over an alternate port.

Step 4: Close the screen and repeat steps 1 - 3 for each remaining port.

For best results, please test the following ports:



1.    25

2.    26

3.    110

4.    143

5.    465

6.    587

7.    993

8.    995

 

 

 

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