Testing your email with Telnet
This article will show you how to test your IMAP and SMTP settings using Telnet
In circumstances where your usual email client is not connecting to your mailbox, using Telnet can helps you to perform a basic assessment of whether your mailbox is functional. This can help you to eliminate your local software as an issue in being unable to receive your mail.
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Please note: the telnet function is disabled by default for most Windows operating systems and must therefore be turned on from the Windows Features menu within your control panel.
How can I use Telnet to test my IMAP email account is working?
Open your command console. In most versions of Windows, click Start, then Run.
From there, type cmd into the command window 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 Generation 2 mailboxes:
telnet imap.secureserver.net 143
* OK [CAPABILITY IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT
LITERAL+ IDLE CHILDREN NAMESPACE LOGIN-REFERRALS UIDPLUS LIST-EXTENDED I18NLEVEL=
1 AUTH=PLAIN] ATLAS/WebFusion Mail Server
01 LOGIN username@domain.com password
01 OK [CAPABILITY IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT
LITERAL+ IDLE CHILDREN NAMESPACE LOGIN-REFERRALS UIDPLUS LIST-EXTENDED I18NLEVEL
=1 AUTH=PLAIN] Logged in.
For Generation 1 mailboxes:
telnet imap.123-reg.co.uk 143
telnet imap.123-reg.co.uk 143
* OK [CAPABILITY IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT
LITERAL+ IDLE CHILDREN NAMESPACE LOGIN-REFERRALS UIDPLUS LIST-EXTENDED I18NLEVEL=
1 AUTH=PLAIN] ATLAS/WebFusion Mail Server
01 LOGIN username@domain.com password
01 OK [CAPABILITY IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT
LITERAL+ IDLE CHILDREN NAMESPACE LOGIN-REFERRALS UIDPLUS LIST-EXTENDED I18NLEVEL
=1 AUTH=PLAIN] Logged in.
This test will indicate whether or not you are able to connect successfully to your email account. If you are able to connect successfully using Telnet, but not through your regular email client, this suggests the issue may be caused by your local software. As such, you should re-check your account settings within your email client in accordance with the vendor's help documentation and our email support pages.
. list "" "*"
Please note: In the code example above, generic values have been used for the mailbox usernames and passwords. When testing your email account connection using telnet, please ensure you have the correct username and password to hand.
How can I use Telnet to test that my email account can send mail via SMTP?
Open your command console. In most versions of Windows, click Start, then Run.
From there, type cmd into the command window 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 will return a message.
For Generation 2 mailboxes:
telnet smtpout.secureserver.net 465
220 mail6.atlas.pipex.net ESMTP Exim 4.71 - "ATLAS SMTP Service" Wed, 13 Jul 201
1 10:47:06 +0100
EHLO smtpout.secureserver.net
250-mail6.atlas.pipex.net Hello hns01-fw.internal.gxn.net [195.224.160.13]
250-SIZE 31457280
250-PIPELINING
250-AUTH PLAIN LOGIN
250 HELP
AUTH LOGIN
334 DXNl4gddhbWU3
cwtui3lAcmlja2ljaeFoYewuY2 (Base 64 encoded username)
334 UGFzc3dvcmQ6
YeGjc3ducmE (Base 64 encoded password)
235 Authentication succeeded
MAIL FROM: emailaddress@domain.com
250 OK
RCPT TO: recipent@theirdomain.com
250 Accepted
DATA
354 Enter message, ending with "." on a line by itself
Subject Test using Telnet
.
250 OK id=4Qgw3m-023484q-I5
For Generation 1 mailboxes:
telnet smtp.123-reg.co.uk 25
220 mail6.atlas.pipex.net ESMTP Exim 4.71 - "ATLAS SMTP Service" Wed, 13 Jul 201
1 10:47:06 +0100
EHLO smtp.123-reg.co.uk
250-mail6.atlas.pipex.net Hello hns01-fw.internal.gxn.net [195.224.160.13]
250-SIZE 31457280
250-PIPELINING
250-AUTH PLAIN LOGIN
250 HELP
AUTH LOGIN
334 DXNl4gddhbWU3
cwtui3lAcmlja2ljaeFoYewuY2 (Base 64 encoded username)
334 UGFzc3dvcmQ6
YeGjc3ducmE (Base 64 encoded password)
235 Authentication succeeded
MAIL FROM: emailaddress@domain.com
250 OK
RCPT TO: recipent@theirdomain.com
250 Accepted
DATA
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 email account. If you see the statement OK, it means that the email message was sent to the recipient.
If you are able to connect successfully using Telnet and send an email, but not through your regular email client, this suggests the issue may be caused by your local software. As such, you should re-check your account settings within your email client in accordance with the vendors help documentation and our email support pages.
If you would like to view all folders within a mailbox you can use the below command when connected via Telnet to the IMAP server.
. list "" "*"
Please note: In the code example above, generic values have been used for the mailbox usernames and passwords.
When testing your email account connection using telnet, please ensure you have the correct username and password to hand.
You will need to encode the username and password using a Base 64 tool such as base64decode.org