18 Jul 2007

Receiving mail OK, but I’m having problems sending mail.

Posted by kilbot | Filed under: Frequently Asked Questions, Hosting FAQ

A common source of problems when sending emails is port 25 blocking. By default most email clients (eg: Outlook, Thunderbird) will use port 25 to connect and communicate with the outgoing mail server. Some ISP‘s block port 25 connections to servers other than their own, in this way they can trace any spam coming from their network.

You can test connections to port 25 using the Telnet command. On PC, go to the Start menu, then select Run, then type

telnet mail.domain.com.au 25

where domain is your domain. On Mac, open the terminal and type

telnet mail.domain.com.au 25

where domain is your domain. Your computer should connect to the mail server and give you a welcome message, such as:

220-host.kilbot.com.au ESMTP Exim 4.68 #1 Thu, 18 Jun 2007 12:58:25 +1000
220-We do not authorize the use of this system to transport unsolicited,
220 and/or bulk e-mail.

If connection the times out it is likely port 25 is being blocked.

Now see if you can connect to your ISP’s outgoing mailserver. Repeat the process above but exchange mail.domain.com.au the appropriate outgoing mailserver, below are some server settings for popular Australian ISPs.

Telstra Bigpond: mail.bigpond.com
OptusNet: mail.optusnet.com.au
iiNet: mail.m.iinet.net.au
Internode: mail.internode.on.net
Netspace: mail.netspace.net.au
TPG Internet: mail.tpg.com.au
Netlink: smtp.netlink.com.au

If you can connect to your ISP’s outgoing mailserver please change the setting in your email client. If you can not connect to any server on port 25 you may be blocked by a firewall on your local network, in this case you will need to adjust your firewall settings to allow outgoing TCP traffic on port 25.