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Common Problems 125144

Oracle Linux 8 – Common Problem 018 – Diagnosis and Fix

🟡 Medium   ⏱ 5–30 min  Last verified: 20 May 2026 Affected versions: Oracle Linux 8 📖 ~3 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 […]

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Common Problems 121638

Postfix Queue Backlog Causing Delayed Email Delivery

🟡 Medium   ⏱ 5–30 min  Last verified: 20 May 2026 Affected versions: Debian 9 📖 ~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 & […]

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Common Problems 122632

Mail Queue Backlog Due to sendmail Misconfiguration

🟡 Medium   ⏱ 5–30 min  Last verified: 20 May 2026 Affected versions: FreeBSD 14 📖 ~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 & […]

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Common Problems 115532

Postfix mail queue stuck and undelivered

🟡 Medium   ⏱ 5–30 min  Last verified: 20 May 2026 📖 ~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 References & Further […]

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How to Configure a Static IP Address with Netplan on Ubuntu 24.04 — step-by-step Linux tutorial on Progressive Robot

How to Install and Configure Postfix Mail Server on Ubuntu 24.04

Postfix is a popular, high-performance Mail Transfer Agent (MTA) that routes and delivers email. This guide installs and configures Postfix as an outgoing SMTP server on Ubuntu 24.04 LTS. Tested and valid on: Ubuntu 24.04 LTS Prerequisites Ubuntu 24.04 LTS server A registered domain name DNS MX records pointing to your server A user with […]

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How to Configure a Static IP Address with Netplan on Ubuntu 24.04 — step-by-step Linux tutorial on Progressive Robot

How to Install and Configure Dovecot IMAP Server on Ubuntu 24.04

Dovecot is a secure, open-source IMAP and POP3 server that works alongside Postfix to deliver email to mail clients. This guide installs and configures Dovecot IMAP on Ubuntu 24.04 LTS. Tested and valid on: Ubuntu 24.04 LTS Prerequisites Ubuntu 24.04 LTS server Postfix installed and configured A domain name with MX records A user with […]

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How to Configure a Static IP Address with Netplan on Ubuntu 24.04 — step-by-step Linux tutorial on Progressive Robot

How to Configure DKIM, SPF and DMARC on Ubuntu 24.04

DKIM, SPF, and DMARC are email authentication standards that prevent spoofing and improve email deliverability. This guide configures all three on a Postfix server on Ubuntu 24.04 LTS. Tested and valid on: Ubuntu 24.04 LTS Prerequisites Ubuntu 24.04 LTS server Postfix installed and running Access to your domain DNS records A user with sudo privileges […]

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How to Install Vagrant and VirtualBox on Ubuntu 24.04 — step-by-step Linux tutorial on Progressive Robot

How to Install GitLab CE on Ubuntu 24.04

GitLab Community Edition is a full-featured DevOps platform that combines Git repository management, CI/CD pipelines, issue tracking, and a container registry in a single application. This guide installs GitLab CE on Ubuntu 24.04 LTS. Tested and valid on: Ubuntu 24.04 LTS Prerequisites Ubuntu 24.04 LTS server Minimum 4 GB RAM (8 GB recommended) A domain […]

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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 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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