Mail Services

How to Configure Postfix Mail Server on FreeBSD 15 — step-by-step FreeBSD 15 tutorial on Progressive Robot

How to Configure Postfix Mail Server on FreeBSD 15

Introduction Deploying configure postfix mail server on a FreeBSD 15 machine differs from Linux in several important ways: packages come from the FreeBSD Ports Collection or the binary pkg repository, services are registered in /etc/rc.conf via sysrc(8), and firewall rules are written in pf.conf(5) syntax. This tutorial stays entirely within the standard base + ports […]

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How to Set Up a DNS Server with Bind9 on Ubuntu 26.04 — step-by-step Linux tutorial on Progressive Robot

How to Install and Configure Postfix Mail Server on Ubuntu 26.04

Postfix is a high-performance, secure, and widely used Mail Transfer Agent (MTA). It handles the SMTP protocol for sending and relaying email. This guide installs and configures Postfix as an internet-facing SMTP server on Ubuntu 26.04 LTS. Tested and valid on: Ubuntu 26.04 LTS Prerequisites Ubuntu 26.04 LTS with a fully qualified domain name (FQDN) […]

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How to Set Up Two-Factor Authentication (2FA) for SSH on Ubuntu 26.04 — step-by-step Linux tutorial on Progressive Robot

How to Install and Configure ClamAV on Ubuntu 26.04

ClamAV is the most popular open-source antivirus engine for Linux. While Linux malware is less common than on other platforms, ClamAV is valuable for scanning files shared with Windows users, email servers, and web upload directories. This guide installs and configures ClamAV on Ubuntu 26.04 LTS. Tested and valid on: Ubuntu 26.04 LTS Prerequisites Ubuntu […]

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How to Set Up a DNS Server with Bind9 on Ubuntu 26.04 — step-by-step Linux tutorial on Progressive Robot

How to Install and Configure Dovecot IMAP Server on Ubuntu 26.04

Dovecot is a secure, open-source IMAP and POP3 server. It allows email clients to retrieve messages stored on the server. Combined with Postfix, Dovecot completes a full mail server stack. This guide installs Dovecot on Ubuntu 26.04 LTS with TLS and Maildir storage. Tested and valid on: Ubuntu 26.04 LTS Prerequisites Ubuntu 26.04 LTS with […]

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How to Install GitLab CE on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Install GitLab CE on RHEL 9

GitLab Community Edition (CE) is a complete, self-hosted DevOps platform that combines Git repository hosting, issue tracking, CI/CD pipelines, container registry, and code review in a single application. Hosting GitLab internally gives organisations full control over their source code without relying on third-party services, making it the preferred choice for teams with data sovereignty requirements […]

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How to Configure OpenDKIM with Postfix on FreeBSD 15 — step-by-step FreeBSD 15 tutorial on Progressive Robot

How to Configure OpenDKIM with Postfix on FreeBSD 15

Introduction This guide explains how to Configure OpenDKIM with Postfix on FreeBSD 15 on FreeBSD 15. FreeBSD uses the pkg(8) binary package manager, rc.conf(5) for service startup configuration, and pf(4) as its primary packet filter. There is no SELinux or AppArmor — instead, FreeBSD provides the MAC (Mandatory Access Control) framework and Capsicum for fine-grained […]

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How to Set Up a DNS Server with Bind9 on Ubuntu 26.04 — step-by-step Linux tutorial on Progressive Robot

How to Configure DKIM, SPF and DMARC on Ubuntu 26.04

DKIM (DomainKeys Identified Mail), SPF (Sender Policy Framework), and DMARC (Domain-based Message Authentication, Reporting and Conformance) are three DNS-based email authentication standards that protect your domain from spoofing and significantly improve email deliverability. This guide configures all three on Ubuntu 26.04 LTS with Postfix. Tested and valid on: Ubuntu 26.04 LTS Prerequisites Ubuntu 26.04 LTS […]

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How to Set a Hostname and FQDN on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Set a Hostname and FQDN on RHEL 9

A server’s hostname is its identity on the network. The fully qualified domain name (FQDN) combines the short hostname with the DNS domain, forming an address like web01.example.com. Many services depend on a correctly configured hostname and FQDN to function properly: email servers use the FQDN in SMTP HELO greetings (incorrect values cause delivery rejections), […]

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Common Problems 116103

Postfix Mail Queue Stuck on Ubuntu 26.04 LTS

🟠 High   ⏱ 5–30 min  Last verified: 6 May 2026 Affected versions: 26.04 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors & Cross-Refs […]

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How to Set Up a Git Server with Gitea on Ubuntu 26.04 — step-by-step Linux tutorial on Progressive Robot

How to Install GitLab CE on Ubuntu 26.04

GitLab Community Edition (CE) is a self-hosted Git repository platform with built-in CI/CD, issue tracking, container registry, and merge request workflows. This guide installs GitLab CE on Ubuntu 26.04 LTS using the official Omnibus package. Tested and valid on: Ubuntu 26.04 LTS Prerequisites Ubuntu 26.04 LTS with at least 4 GB RAM and 2 CPUs […]

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