Linux Tutorials - Herong's Tutorial Examples

∟Email Client Tools - Mail User Agents (MUA)

∟Thunderbird to Accept POP3S Certificate Exception

This section provides a tutorial example on how to handle POP3S server Certificate Exception on Thunderbird. Just click 'Confirm Security Exception' to accept and store the default certificate provided by Dovecot server.

If you are running a POP3S (POP3 with SSL/TLS) service with Dovecot. Dovecot will be using a dummy self-signed root certificate by default.

When you connect Thunderbird to this POP3S service for the first time, you will get certificate exception. Don't worry. Here is how you can handle this exception.

1. Click "Confirm Security Exception". This tells Thunderbird to accept and store this certificate.

2. Click "Get Messages" to continue retrieving emails from the POP3S server.

Thunderbird POP3S Server Certificate Exception
Thunderbird POP3S Server Certificate Exception

If you are curious about this dummy self-signed root certificate, click "Thunderbird > Preferences > Privacy & Security" menu. Then click "Manage Certificates" to open it. The dummy certificate shows the following: 

Subject Name
  Organizational Unit: IMAP server
          Common Name: imap.example.com
        Email Address: postmaster@example.com
...

The subject name, IMAP server, suggests that Dovecot is sharing the same dummy certificate for both IMAPS and POP3S service.

If you don't like this default certificate, Read Dovecot to replace it with your own certificate.

Table of Contents

 About This Book

 Introduction to Linux Systems

 Cockpit - Web Portal for Administrator

 Process Management

 Files and Directories

 Users and Groups

 File Systems

 Block Devices and Partitions

 LVM (Logical Volume Manager)

 Installing CentOS

 SELinux - Security-Enhanced Linux

 Network Connection on CentOS

 Internet Networking Tools

 Software Package Manager on CentOS - DNF and YUM

 vsftpd - Very Secure FTP Daemon

 Postfix - Mail Transport Agent (MTA)

 Dovecot - IMAP and POP3 Server

►Email Client Tools - Mail User Agents (MUA)

 "mailx" Command - Send and Read Emails

 "Alpine" - Terminal-Based Email Client

 Thunderbird Installation on macOS

 Thunderbird Configuration for POP3S and SMTP

►Thunderbird to Accept POP3S Certificate Exception

 Thunderbird Configuration for IMAPS and SMTP

 Thunderbird Configuratin for SMTPS Service

 macOS Mail Auto Configuration

 macOS Mail Manual Configuration

 Accept Certificate Exception in macOS Mail

 Windows 10 Mail Configuration Failed

 SSL/TLS Connection Issue in Windows 10 Mail

 LDAP (Lightweight Directory Access Protocol)

 Administrative Tasks

 References

 Full Version in PDF/EPUB