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Email Troubleshooting - Testing POP/IMAP

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Legacy DV and VPS Hosting

Legacy DV Developer Hosting

  • Applies to: All DV
    • Difficulty: Medium
    • Time Needed: 20
    • Tools Required: SSH, root or sudo access

Overview

This guide will show you how to test the POP3 and IMAP services running on your DV server. We also show you remedies to common problems.

Requirements

Before you start, this article has the following dependencies:

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Checking Service Availability

Log in to your server over SSH and input the following commands:

Test POP3

telnet localhost 110

Test IMAP

telnet localhost 143

If your POP3/IMAP services are running, you will see responses similar to the following:

POP3

Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
+OK Hello there

IMAP

Trying 127.0.0.1...
 Connected to localhost.localdomain (127.0.0.1).
 Escape character is '^]'.
 * OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION STARTTLS] Courier-IMAP ready. Copyright 1998-2004 Double Precision Inc. See COPYING for distribution information.

Testing login capability

You can perform a login attempt over telnet to these services quite easily.

POP3

Upon making the initial conneciton attempt, you should get the +OK Hello There message. Now do the following:

user username@example.com
+OK Password required.
pass PASSWORD
+OK logged in.
list
+OK POP3 clients that break here, they violate STD53.

TIP:

The +OK messages in between commands are server responses.

IMAP

Upon making the initial connection attempt, you should get the * OK [CAPABILITY IMAP4rev1...] message. Now do the following:

01 login username@example.com <password>

You should get the following response from the server:

01 OK LOGIN Ok.

Troubleshooting

If you make a connection attempt through either port 110(POP3) or 143(IMAP) and get a response similar to the following:

Trying 127.0.0.1...
telnet: connect to address 127.0.0.1: Connection refused
telnet: Unable to connect to remote host: Connection refused

This is an indication that the Courier-IMAP service is not running.

First, check if courier-imap is running:

ps ax | grep courier

If you see no output, try to start the Courier-IMAP service from the command line:

service courier-imap start

Check /var/log/messages and /usr/local/psa/var/log/maillog for possible start up errors:

cat /var/log/messages
cat /usr/local/psa/var/log/maillog

If after attempting to restart the service you are still encountering a connection refused error message, try to run courier-imap with the default configuration. To do this, backup the original configuration files:

  • /etc/courier-imap/pop3d for POP3
  • /etc/courier-imap/imapd for IMAP

Replace these with the default distribution configuration files:

  • /etc/courier-imap/pop3d.dist for POP3
  • /etc/courier-imap/imapd.dist for IMAP

Now, restart courier-imap and try to login again. In case of success, compare the original and *.dist files in order to find the option that may have caused the problem.

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