Set up DMARC (verification) for Postfix on Debian server This tutorial will be showing you how to set up OpenDMARC with Postfix SMTP server on Debian/Ubuntu server to block email spoofing and spam. Security Networking
DMARC - Domain-based Message Authentication, Reporting and Conformance What is DMARC DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication method that verifies a message came from a legitimate sender. DMARC is an open standard for email authentication that helps to prevent fraudsters from forging (spoofing) your domain. DMARC checks that the From field matches the domain in DKIM and SPF authentication checks. DMARC also tells email servers how to handle messages that fail these checks and allows recipients to receive reports on emails that fail authentication. Networking Security
Explanation DKIM (DomainKeys Identified Mail) in all details DKIM (DomainKeys Identified Mail) is a system that lets your official mail servers add a signature to headers of outgoing email and identifies your domain’s public key so other mail servers can verify the signature. As with SPF (Sender Policy Framework helps keep your mail from being considered spam. It also lets mail servers detect when your mail has been tampered with in transit. Networking Security
SPF - Sender Policy Framework Email Message Structure To understand how SPF (Sender Policy Framework) and DKIM works is to know the difference between email envelope and email header . Short Definition: Sender Addresses in E-Mails Like paper mail letters, e-mail messages have at least two kinds of sender addresses: one on the envelope and one in the letterhead. The envelope sender address (sometimes also called the return-path) is used during the transport of the message from mail server to mail server, e. Networking Security
What is email envelope and email header The key for understand smtp protocol is learn, what is difference between email envelope and email header. Another words, what is email envelope vs email header. Networking Security
How to Test an SMTP Server with Telnet command line How to test SMTP and IMAP servers using the telnet command-line Linux Networking Windows
Postfix - how log email headers like From, To and Subject This is a little trick for Postfix, it lets you log the subject, from and to of all the emails postfix sends (or which pass through it if you run it as a relay). It comes in handy when you need to debug an email issue and need to confirm your mailserver has sent the message. Networking
Most secure SSL/TLS configuration for Apache, Nginx, Postfix, Dovecot, HAProxy and other What is a cipher suite? Cipher suites decide how secure, compatible and fast your HTTPS website is. A cipher suite is a set of information that helps determine how your web server will communicate secure data over HTTPS. A web server uses certain protocols and algorithms to determine how it will secure your web traffic. These are the ingredients of a secure connection. A cipher suite is essentially a list of those ingredients. Security Linux Networking Web Servers
