Checking your outgoing mail server (Is Port 25 blocked?)

Introduction

Many email clients and services use port 25 for SMTP to send out emails. However an ISP (Internet Service Provider) may block port 25 in order to prevent spamming by its customers. This article will show you how you can check to see if Port 25 is blocked on your network.

Before you start

This article assumes that you know how to get to a command prompt on your computer. If you need help with this, please search Google on how to use telnet.

READ ME FIRST

This article is provided as a courtesy. Installing, configuring, and troubleshooting third-party applications is outside the scope of support provided by Linuxweb.

Instructions

  1. Type the following command:
    telnet example.com 25
  2. View Results:
    If Port 25 is not blocked, you will get a successful 220 response (text may vary).
    Trying 64.13.192.208...
    Connected to example.com.
    Escape character is '^]'.
    220 cl34.gs01.gridserver.com ESMTP Exim 4.63 Tue, 24 Jun 2008 13:45:04 -0700
    If Port 25 is blocked, you will get a connection error or no response at all.
    Trying 64.13.192.208...
    telnet: connect to address 64.13.192.208: Connection refused
    telnet: Unable to connect to remote host

    TIP:

    You can use this same technique to check if Port 587 is blocked as well.  Just use the following command:

     telnet example.com 587

FAQs

Q: What can I do if port 25 is blocked?
A: You may also choose to use the alternate Port 587. All of our customers should contact their ISP (Internet Service Provider) if Port 25 is blocked.  In many instances, they will let you use their outgoing SMTP servers.

Resources

List of common SMTP Servers:

@lantic smtp.lantic.net
Cell C mail.cmobile.co.za
Global smtp.global.co.za
Iafrica smtp.uunet.co.za
smtp.iafrica.com
iBurst smtp.wbs.co.za
smtp.iburst.co.za
Internet Solutions smtp.isdsl.net (ADSL)
smtp.dial-up.net (56k dial up on IS)
MWEB smtp.mweb.net (ADSL)
smtp.mweb.co.za (56k dial-up)
MTN smtp.mtn.co.za
Neotel smtp.neomail.co.za
Netactive smtp.netactive.co.za
SAIX (Telkom) smtp.saix.net
Sentech smtp.sentech.co.za
Telkom smtp.saix.net (ADSL)
smtp.telkomsa.co.za (56k dial up)
smtp.telkomsa.net
Tiscali smtp.tiscali.co.za
Vodacom smtp.vodacom.co.za
Web Africa smpt.wa.co.za

Was this answer helpful?

 Print this Article

Also Read

What are my incoming and outgoing server addresses

Your Incoming Mail Server (POP3) and Outgoing Mail Server (SMTP) server address is...

Email account configuration for Outlook 2010

Step by Step insctruction to setup your email account with Outlook 2010 Open Outlook. If this...

How do I stop the bounce messages?

I can no longer receive mail in my mail box. Users are getting emails back to them saying that...

Default pop3 and SMTP Ports

Sometime setting up all the various email configurations can be extremly confusing, especially...

Email account configuration for an iPad

These easy to follow guides provide step-by-step instructions on how to setup or troubleshoot...

Powered by WHMCompleteSolution