Business email on your own domain, without running Postfix.
MailStack is a complete mail server — inbound SMTP, authenticated sending, and a real-time webmail client — that you deploy once and resell to as many domains as your plan allows.
Accounts are created by invitation — there is no self-signup at any tier.
Live on your domain the same day
Add your domain
We generate a DKIM keypair the moment you add it, and hand back every DNS record to publish — MX, SPF, DMARC, DKIM and your webmail CNAME.
Publish the records
Copy them into your DNS provider. We chunk the DKIM key for providers that cap TXT values at 255 bytes, so nothing silently truncates.
Create mailboxes
Add users under your domain. Each one logs in at webmail.yourdomain.com — your brand in the address bar, not ours.
What you get
Authenticated from day one
Every outbound message is DKIM-signed with your domain's own key. SPF and DMARC records are generated alongside it, so you pass alignment checks instead of debugging them.
Real-time inbox
Mail appears the instant it is received over a WebSocket — no polling, no refresh button, no five-minute IMAP sync.
Genuinely multi-tenant
Every domain, mailbox and message is scoped server-side to the account that owns it. One tenant can never see another's mail, including over the realtime feed.
No open relay, ever
The SMTP receiver accepts mail only for mailboxes that actually exist here. Everything else gets a 550 at RCPT TO.
Your infrastructure
No Postfix, no Dovecot, no Docker. One Node process is the mail server — deploy it on a VPS you control and keep the data on your own disk.
Untrusted HTML, handled
Received email bodies render inside a fully sandboxed iframe. Nothing in a message can run scripts or reach your session.
What it is not
Running your own mail is a real operational commitment, and we would rather you know the edges before you buy than after.
- No IMAP or POP3 yet. Mail is read through the webmail client, not Outlook or Apple Mail.
- A new sending IP starts cold. Expect spam-folder placement until reputation builds, or relay through an established provider while you warm up.
- Port 25 must be open. Many cloud providers block it on new accounts and need a support request to unblock.
Ready to move your mail in-house?
Pick a plan, or tell us what you are running today and we will tell you honestly whether this is a good fit.