Configure a clean dedicated IP for an SMTP VPS on AlmaLinux
Step-by-step setup for a clean dedicated IP on an SMTP VPS in Vietnam running AlmaLinux 9: rDNS, SPF, DKIM, DMARC, port 25, and sender reputation checks.
Set up a VPS for running an email marketing system
Hướng dẫn kỹ thuật dựng hệ thống email marketing tự quản trên VPS: kiến trúc, SMTP, chống spam, theo dõi chiến dịch, và đo hiệu suất gửi.
How to check if a VPS IP is blacklisted
Learn how to check if a VPS IP is blacklisted: DNSBL lookup tools, RBL checks, sender reputation on SMTP, and how to fix blacklisted IPs on a Linux VPS.
Why VPS emails land in spam and how to fix it
This post explains why emails sent from a VPS land in spam and gives you a step-by-step, command-level fix for SPF, DKIM, DMARC, rDNS, and IP warmup that actually gets mail into the inbox.
Set up rDNS on an SMTP VPS in 2026
A practical walkthrough to set up rDNS on an SMTP VPS, why it matters for email deliverability, what to request from your provider, and how to verify it with dig and host.
Cheap Linux VPS Vietnam with multiple IPv4 for PowerMTA
Hướng dẫn cấu hình cheap VPS Ubuntu Vietnam với multiple IPv4 addresses cho PowerMTA email delivery, tối ưu sender reputation.
Warming up a new sending IP: a realistic 30-day schedule
Learn the correct 30-day IP warmup schedule for email sending. A day-by-day volume table, technical commands, and real-world advice to protect your sender reputation.
SPF, DKIM and DMARC on a self-hosted SMTP server
A step-by-step guide to configuring SPF, DKIM, and DMARC on your self-hosted SMTP server to improve email deliverability and prevent spoofing.
Port 25 access on a VPS: why most providers block it and when it is opened
Understand why most VPS providers block port 25 by default, how to request it unlocked, and when it makes sense for your email infrastructure.
A clean dedicated IP for outbound email: what clean actually means
Learn what a clean dedicated IP for outbound email really means: no blacklist history, proper rDNS, isolated reputation. Essential reading for anyone operating a self-hosted mail server.