How can I use Telnet to test that my email account can send mail via SMTP?

This article applies to 123-reg email accounts.

This article explains how to use the telnet command in your command prompt console to establish whether your e-mail account can send emails via the the 123-reg SMTP server.

In circumstances where your usual e-mail client software is not connecting to the 123-reg SMTP server to send emails, using telnet helps you to perform a basic assessment of whether your email account is functional. This can help you to eliminate your local software as an issue in being unable to send your mail.

Please be aware that for Windows Vista & Windows 7, the telnet function is by default disabled and therefore it must be turned on from the Windows Features menu within the control panel.


Open up your command console - in most versions of Windows, click Start, then Run, type cmd and hit Enter.


Enter the text as shown in Bold in the example command box below, hitting Enter at the end of each line. For each successful command you issue, the server a return the message.

telnet 25

220 ESMTP Exim 4.71 - "ATLAS SMTP Service" Wed, 13 Jul 201 1 10:47:06 +0100

EHLO Hello []

250-SIZE 31457280



250 HELP


334 DXNl4gddhbWU3

cwtui3lAcmlja2ljaeFoYewuY2 (Base 64 encoded username)

334 UGFzc3dvcmQ6

YeGjc3ducmE (Base 64 encoded password)

235 Authentication succeeded


250 OK


250 Accepted


354 Enter message, ending with "." on a line by itself

Subject Test using Telnet


250 OK id=4Qgw3m-023484q-I5

This test will indicate whether or not you are able to connect successfully to send email from your e-mail account and if you see the statement OK it means the that the email message was sent to the recipient.

If you are able to connect successfully using telnet and send a email, but not through your regular e-mail client, this suggests the issue may be caused by your local software and you should re-check account settings in your e-mail client in accordance with the vendors help documentation and our e-mail support pages.

Please note: When testing your e-mail account connection using telnet, please ensure you have the correct e-mail account username and e-mail account password to hand, if you have forgotten your email login details click here to find out how to retrieve them.

You will need to encode the email account user name and password using a Base 64 tool such as


Answer options

Your feedback was successfully added.

Answer tracking


Watch the content of this article for changes.