MailStack
MailStack is an open-source, self-hosted mail server and shared team inbox for controlled, receive-only business email.
What MailStack is
MailStack is an open-source, self-hosted mail server and shared team inbox for controlled, receive-only business email. Its web inbox offers search, message previews, attachment filters, read and unread states, live polling, and browser notifications. Administrator and ordinary-user accounts can access shared mailboxes through memberships, with object-level isolation between mailboxes. MailStack ingests messages through Maildir, protects against duplicate delivery, and includes recovery for malformed messages. It sanitizes HTML, blocks remote and active content, and stores attachments in protected storage for authorized downloads. Listed security controls include Argon2 password hashing, login throttling, CSRF protection, secure production cookies, and least-privilege database access. The reference deployment receives mail through Postfix and delivers it using Dovecot LMTP; it does not provide public SMTP submission, IMAP, POP3, or open relay. The supported setup is a single-node Ubuntu Server 24.04 LTS VPS with public DNS and reachable inbound ports 25, 80, and 443. The free project is licensed under GNU AGPL version 3.0 or later and includes health endpoints, audit logging, and backup and recovery tools.
Good
- Open-source and self-hosted
- Mailbox access can be isolated by object
- Includes HTML sanitization and protected attachment storage
- Lists backup, restore, rollback, and verification tooling
- No plan price is listed beyond the free open-source plan
Watch out
- Reference setup is single-node only
- Does not provide IMAP or POP3
- Excludes public SMTP submission and open relay
- Requires Ubuntu Server 24.04 LTS and reachable inbound ports
Who it suits
MailStack is intended for teams that need a self-hosted business inbox with shared mailboxes and per-user authorization. It suits administrators able to operate the specified single-node Ubuntu VPS deployment.
Verdict
MailStack focuses on controlled inbound mail and shared team access rather than general-purpose mail protocols or outbound campaigns. Its deployment requirements and exclusions make it important to confirm that the setup matches a team's mail-flow needs.
Plans and prices
From MailStack's own pricing page, checked 4 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Open source | Free | Self-hosted · single-node reference deployment |
The facts
Each one read from MailStack's own pages, with the date it was checked.
What it does
- Attachments
- Attachments are stored in confined protected storage and downloaded through authorized routes.checked 4 Oct 2026
- Deployment requirements
- The supported reference deployment is a single-node Ubuntu Server 24.04 LTS VPS with public DNS and reachable inbound ports 25, 80, and 443.checked 4 Oct 2026
- Inbox features
- The web inbox supports search, pagination, read and unread state, attachment filters, message previews, live polling, and browser notifications.checked 4 Oct 2026
- Intended users
- MailStack is designed for teams needing self-hosted business inboxes with per-user shared mailbox authorization and controlled receive-only email.checked 4 Oct 2026
- License
- The source code is licensed under GNU AGPL version 3.0 or later.checked 4 Oct 2026
- Mailbox access
- It provides administrator and ordinary-user accounts, object-level mailbox isolation, and shared mailbox memberships.checked 4 Oct 2026
- Mail flow
- The reference deployment receives mail via Postfix and delivers it through Dovecot LMTP; it excludes public SMTP submission, IMAP, POP3, and open relay.checked 4 Oct 2026
- Message handling
- MailStack uses Maildir ingestion with duplicate-delivery protection, malformed-message recovery, HTML sanitization, and blocking of remote and active content.checked 4 Oct 2026
- Notable limits
- The reference deployment excludes public user registration, outbound campaigns, multi-node or high-availability deployment, and a public administrative API.checked 4 Oct 2026
- Operations
- The project lists health and readiness endpoints, structured security audit logging, and backup, restore, rollback, and verification tooling.checked 4 Oct 2026
- Purpose
- MailStack is an open-source, self-hosted mail server and shared team inbox for controlled, receive-only business email.checked 4 Oct 2026
- Security
- Listed controls include Argon2 password hashing, login throttling, CSRF protection, secure production cookies, and least-privilege database access.checked 4 Oct 2026
- Support
- Vib Tools lists product support by email and provides a Bangladesh head office address in Kurigram, Rangpur.checked 4 Oct 2026
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