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)
References
Full Version in PDF/EPUB