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What is BillionMail? A plain-English introduction

BillionMail is a free, open-source mail server and newsletter platform made by the team behind aaPanel. It gives you two things in one install: a real mail server that sends and receives email, and a newsletter tool with contact lists, templates, campaigns and statistics.

Want to see it in action? Here is our full BillionMail on aaPanel video walkthrough:


If you have ever paid Mailchimp, Brevo or a similar service per subscriber, BillionMail is the self-hosted alternative: you pay for a server, and you can send as much as your server and your reputation allow.

What you get

• Email marketing: contact groups, CSV import, tags, HTML templates, scheduled campaigns (called "tasks"), and open, click and bounce statistics.
  
• Mailboxes and webmail: real addresses like support@ and admin@ on your domain, with Roundcube webmail and IMAP/SMTP for mail apps.
  
• Send API: let your website or app send receipts, password resets and other transactional email through it.
  
• SMTP relays: optionally hand delivery to Gmail, Mailgun, Amazon SES, SendGrid or any SMTP server.
  
• A DNS helper: it shows the exact MX, SPF, DKIM, DMARC and PTR records to add, and checks them for you.
  

What runs inside
BillionMail isn't a mail server written from scratch. It ties together well-known, trusted parts, each in its own Docker container:

• Postfix sends and receives mail.
  
• Dovecot stores mailboxes and serves IMAP and POP.
  
• Rspamd filters spam and signs outgoing mail with DKIM.
  
• Roundcube is the webmail.
  
• PostgreSQL and Redis store your data and keep things fast.
  

You can see all of them under Settings > Service, with a restart button for each.

Who it's for
BillionMail is a good fit if you:

• send newsletters or product updates to people who signed up,
  
• want your subscriber list and statistics on your own server,
  
• are comfortable editing DNS records and reading an error message.
  

It's probably not the right choice if you need to send a large volume tomorrow from a brand-new server, or you never want to think about deliverability.

The honest part: deliverability is your job
Installing BillionMail takes about ten minutes. Getting Gmail and Outlook to trust your mail takes a bit more care. With a hosted service, they handle that for you. With your own server, you need:

• outgoing port 25 open at your VPS provider,
  
• correct DNS records: MX, SPF, DKIM and DMARC,
  
• a reverse DNS (PTR) record that matches your mail server name,
  
• a server that introduces itself with the right name (not "localhost"),
  
• a slow start (warm-up) on a new IP address, and a clean, opt-in list.
  

None of this is hard, and our guides walk through every step. In our own test, a fresh BillionMail server went from 89/100 (B) to 95/100 (A) on a deliverability test after fixing these points.

What you need to start

• A VPS with about 2 CPU cores and 4 GB RAM (it runs several containers).
  
• A domain where you can edit DNS.
  
• aaPanel installed (or Docker, if you prefer the command line).
  

Next steps

1. Install BillionMail from aaPanel
   
2. Set up DNS: MX, SPF, DKIM, DMARC and PTR
   
3. Free SSL, and the hostname fix
   
4. Send your first newsletter
   
5. Test deliverability and fix problems
   

Each guide is in this forum. Questions? Ask in aaPanel BillionMail Support and paste the exact error message.

More BillionMail how-to guides

• Send API for transactional email
  
• WordPress email through BillionMail SMTP
  
• Import contacts, groups and tags
  
• Email templates explained
  
• SMTP relay with Amazon SES, Brevo or Mailgun
  
• Mailboxes and webmail
  
• Campaign analytics explained
  
• IP warm-up plan
  
• Move from Mailchimp or Sendy
  
• Add a second sending domain
  

Sources (checked October 2026): BillionMail on GitHub · billionmail.com. Tested on BillionMail 4.9.0 installed through aaPanel.