Linode SMTP Setup Guide (Port 25)

Prerequisites: Linode Port 25 Open account ($130 from our marketplace), a domain name, basic Linux knowledge.

Step 1: Create instance. Log into cloud.linode.com, create Nanode 1GB for low volume or 2GB for higher. Choose the datacenter closest to your audience. Use Ubuntu 22.04 LTS.

Step 2: Set Reverse DNS. Linode control panel → your instance → Network → IP Addresses → Edit RDNS. Set PTR to match your mail hostname (mail.yourdomain.com). Critical for deliverability.

Step 3: Install Postfix. Run: apt update && apt install postfix mailutils -y. Choose "Internet Site" and enter your domain.

Step 4: Configure DNS records: - SPF: TXT record at yourdomain.com: "v=spf1 ip4:YOUR_IP ~all" - DKIM: Install opendkim, generate keys with opendkim-genkey, add public key as TXT at mail._domainkey.yourdomain.com - DMARC: TXT at _dmarc.yourdomain.com: "v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com"

Step 5: Test with mail-tester.com. Aim for 9/10+ score before sending real traffic.