This Project is Under Develepment

A demo video on how to set up this project on a server is coming soon.

This project started as a fun experiment but has grown into something more. Right now, it's a simple mail server for sending and receiving emails. Future updates will add:

• Mail Exchanger (IMAP) – Use Gmail, Outlook, Yahoo, or Hotmail to send and receive emails.
• Extra Features – SMTP relay, IP/domain whitelisting & blacklisting.
• AI Email Optimization – Smart suggestions to improve email performance.
• Security & Anti-Spam – AI-driven spam filtering and fraud detection.
• User Controls – Rate limits, storage alerts, email forwarding, and aliases.
• Calendar Integration – Works with Google Meet, Teams, and Cal.com.
• Developer API – Easy-to-use API for automating emails in your apps.

SMTP Server Setup Guide

Prerequisites

• A registered domain name

• A server with a static IP address

• SSL/TLS certificate for secure email transmission

Basic Server Setup

• Configure your server with a static IP address

• Ensure your firewall allows SMTP traffic (ports 25, 465, and 587)

• Set up reverse DNS (PTR record) for your mail server IP (- Most Important)

Clone the Repository

Use Any Package Manager, I'm just using bun.sh

1. Install Dependencies First (Recommended) bun install

2. Build the Applications bun run build, dont use bun build

3. Start with command bun run dev (Development) and bun run start with root permissions (Incase not able to start then use sudo node ./build/main.js)

NOTE

You will find two server file config (Incoming and Outgoing) and 2 server listening at 25 and 587. We can do it one, but we have to manage incoming and outgoing in same file, which is a mess, complicates the code. Moreover you have full controll to run multiple diffrente mail server like mx.domain.com, mx2.domain.com etc and for sending {smtp,mail}.domain.com (which ever is suitable).

DNS Records Configuration

How to genrate DNS Records

• bash chmod +x run.sh

• bash ./run.sh 2 .

• Go to src -> start.ts

• Open and replace your_domain with your domain name

const records = new DNSRecordGenerator("cirrusmail.cloud").generateAllRecords();

and Run this File, Records will create in records.json File in root directory.

Essential DNS Records

1. A Record

• Create mail.yourdomain.com pointing to your server IP
• Ensure the hostname matches SSL certificate

2 .PTR Record

• Contact your hosting provider to set up reverse DNS
• Should match your mail server's hostname

Share your Mailserver hostname, who ever wants to use your server and tell them to create MX Record pointing your server.

• Point to your mail server hostname
• Set priority (e.g., 10 mail.yourdomain.com)

Anti-Spam DNS Records

1. SPF Record (TXT)

• Add record: v=spf1 ip4:YOUR_IP mx -all
• Prevents email spoofing
• Specifies authorized IPs/servers

2. DKIM Record

• Generate DKIM keys
• Add public key to DNS as TXT record
• Format: default._domainkey.yourdomain.com

3. DMARC Record

• Add TXT record: _dmarc.yourdomain.com
• Define policy for failed authentications
• Set up reporting (optional)

Note: Required Ports => 25, 587

Port 25 is used for receiving mails and outbound traffice to send mail from your server to another mail server

Port 587 is used for to connection to your mail server and create transport which send mail and process the mail , how it is going to deliver via Direct or Relay

Generate SSL Ceritificate for using STARTTLS to prevent spam. Dont use Self Signed Certificate

Mail Server SSL Certificate Setup

Simple guide to secure your mail server with Let's Encrypt/ZeroSSL certificates using Certbot. This setup enables encrypted SMTP connections and works with any transport method (relay or direct delivery).

Prerequisites

Linux server with root access

Domain with DNS A record pointing to your server

Port 80 temporarily available for verification

Installation Steps

Install Certbot:

sudo  apt  update

sudo  apt  install  certbot

Generate certificate:

sudo  certbot  certonly  --standalone  --preferred-challenges  http  -d  mail.domain.com

Certificate locations:

Certificate: /etc/letsencrypt/live/mail.domain.com/fullchain.pem

Private key: /etc/letsencrypt/live/mail.domain.com/privkey.pem

Update Your .env

MAIL_HOST="mail.domain.com"

MAIL_SERVER_IP="127.0.0.1"

MAX_EMAILS_PER_MINUTE=5

TLS_PRIVATE_KEY_PATH="/etc/letsencrypt/live/mail.domain.com/privkey.pem"

TLS_CERTFICATE_PATH="/etc/letsencrypt/live/mail.domain.com/fullchain.pem"

Testing

• Run mail server tests:
• Verify all DNS records
• Test SMTP authentication
• Check TLS encryption
• Verify reverse DNS
• Test sending/receiving

Use external tools:

Go and Test Your Mail Server here , it should be like in given Image https://mxtoolbox.com/diagnostic.aspx