SSL/TLS Secure Connections with Postfix Server

Email Tutorials - Herong's Tutorial Examples

∟SSL/TLS Secure Connections with Postfix Server

This chapter provides introductions and tutorial examples about SSL/TLS secure connections with Postfix server. Topics include testing SSL/TLS connections with 'openssl s_client' commands; replacing the default self-signed server certificate; requesting and installing a CA-signed server certificate.

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SSL/TLS Options on Postfix Server Ports

SMTP with STARTTLS on Port 25 in Postfix

"openssl s_client" Test SSL/TLS Connection

SMTPS Service on Port 465 in Postfix

Replace Self-Signed Root Certificate on Postfix

Install CA Signed Server Certificate on Postfix

Takeaways:

Postfix server listens on 3 TCP ports, 25, 465, and 587, for incoming POP3 and IMAP connection requests
Postfix server accepts SMTP requests at port 25 with STARTTLS command to start SSL/TLS connections manually. These are often referred as Opportunistic TLS connections and used primarily for mail relay communications.
Postfix server accepts SMTP requests at port 465 with SSL/TLS connections started automatically. These are often referred as SMTP (SMTP over SSL/TLS) connections.
Postfix server accepts SMTP requests at port 587 with STARTTLS command to start SSL/TLS connections manually. These are often referred as Opportunistic TLS connections and used primarily for mail submission communications.
"openssl s_client" command is a very powerful tool for testing SSL/TLS connections.
You should replace the default self-signed server certificate with a new one that matches your Postfix server identity.
You should request and install a CA self-signed server certificate to avoid certificate exceptions in email clients.

Table of Contents

About This Book

Introduction to Email

Postfix - Mail Transport Agent (MTA)

►SSL/TLS Secure Connections with Postfix Server

Dovecot - IMAP and POP3 Server

SSL/TLS Secure Connections with Dovecot Server

Email Client Tools - Mail User Agents (MUA)

Mozilla Thunderbird - Mail User Agents (MUA)

PHPMailer - PHP Package for Sending Emails

Email Message Format and Headers

References

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