Anyone weighing a mailcow alternative has usually already run mailcow, or has read enough of the docs to see what the commitment looks like. It's a genuinely good piece of software — a complete, well-maintained mail stack you can stand up in an afternoon and own entirely.
So a mailcow alternative isn't a verdict on the software. The question is never whether it works. It's whether the ongoing cost of running it is lower than paying someone else, and that cost is mostly not the server bill.
What Self-Hosting Actually Asks Of You
Mailcow's own prerequisites are refreshingly blunt, and they're the right place to start. You need a fresh server with a public IP address, and their documentation states that 6 GiB of RAM plus 1 GiB of swap suits most private installations, with 8 GiB recommended for five to ten users.
You also need these ports open inbound: 25, 80, 443, 465, 587, 993, 995 and 4190. The PTR record for your IP has to match the FQDN of the host. The docs note that ClamAV and the Flatcurve full-text engine are greedy with memory and can be disabled — which tells you what the first tuning session will be about.
None of that is unreasonable. It is, however, a list, and every item is a thing that can be wrong at the exact moment you need mail to work.
The Reason Most People Want a Mailcow Alternative
Here's the item no requirements list can state, and the single biggest reason people go looking for a mailcow alternative: a new IP address has no sending reputation, and you cannot install one.
Your server is technically perfect — SPF, DKIM, DMARC, matching PTR, TLS — and Microsoft still files your mail in Junk for weeks. That isn't a misconfiguration you can fix in an evening. It's the receiving side deciding it has never seen your IP before and choosing caution. Warming an IP takes consistent, low-volume, well-received sending over time, and one bad week undoes it.
Two related things bite. Plenty of hosting providers block outbound port 25 by default and only open it after review, so the plan can fail before it starts. And IP ranges carry history — you can be assigned an address that a previous tenant burned, and inherit a blocklist entry you did nothing to earn.
A hosted provider hands you a maintained, monitored pool that's already trusted. That's most of what you're actually paying for.
Who Does the Work at 3am
The install takes an afternoon. The operating takes years.
Certificates renew and occasionally don't. Docker images update, sometimes with breaking changes. Disks fill, usually with mail you can't delete. A CVE lands in a component you'd forgotten was in the stack. Spam rules drift and need retraining. Backups have to be tested by restoring them, because a backup nobody has restored is a hypothesis.
None of this argues for a mailcow alternative on its own. For one technical person running mail for themselves, it's a fine hobby and often an enjoyable one. For a business, the honest question is what happens when that person is on holiday and mail stops. If the answer is "nothing good," you don't have a mail server — you have a dependency on one employee.
The Real Cost Comparison
The comparison people run before choosing a mailcow alternative is a VPS bill against a subscription, and mailcow wins it easily. Here's the fuller version:
| What it costs | Self-hosted mailcow | Hosted |
|---|---|---|
| Server | ~$20–40/month for 8 GiB | Included |
| Backups, off-site | Your problem, your bill | Included |
| IP reputation | Weeks of warm-up, ongoing risk | Maintained pool |
| Upgrades and CVEs | Your evenings | Included |
| Someone awake when it breaks | You | Included |
| Software licence | Free, open source | n/a |
Mailcow itself is free and that's a real advantage — no per-mailbox pricing, ever, at any scale. If your time genuinely costs nothing and you enjoy the work, self-hosting is cheaper and this article is not for you.
If your time has a price, put a number on the hours and rerun it. The answer flips for most people at around two hours a month, and mail administration rarely stays under two hours a month.
What a Hosted Mailcow Alternative Gives Back
Beyond the operational load, three capabilities are awkward to build yourself even on a stack as complete as mailcow.
Reading mailboxes you don't host. Clients staying on Google Workspace or Microsoft 365 can't be self-hosted by definition. Connecting to them over IMAP puts their mail in the same list as everything else, with replies leaving through their own provider so authentication stays aligned. See the unified inbox.
Migration that verifies itself. An IMAP copy can silently leave a folder short and still report success. A move that reconciles unique Message-IDs on both sides afterwards tells you which folder came up short — that's bulk migration, and it matters most on the day you leave a self-hosted box.
Provisioning through an API. Mailcow has an API and it's decent. What's different here is that the same operations are exposed to an assistant through an MCP server, so creating a domain, its DNS records and thirty mailboxes is a request rather than a script.
The ordinary things are the same on both sides, and should be: IMAP, SMTP, Sieve filters, CalDAV and CardDAV, and a webmail client.
When You Should Absolutely Keep Self-Hosting
A mailcow alternative is the wrong move if any of these are true:
- Data sovereignty is a hard requirement and the mail must sit on hardware you control.
- You have thousands of mailboxes, where per-account pricing stops making sense at any provider.
- Running infrastructure is your job or your hobby, and the hours aren't a cost.
- You need something no hosted provider exposes — custom Rspamd rules, unusual Dovecot plugins, direct database access.
- Your IPs are already warm and behaving, which is the asset that's hardest to replace.
That last one is worth weighing properly. A working, trusted, well-behaved self-hosted server is genuinely valuable, and rebuilding that trust elsewhere isn't instant. If yours is running well, keep it.
The Verdict, Whoever You Are
Self-hosting is a fair trade when running infrastructure is the point, and a poor one when mail simply has to work.
One person who enjoys this. Keep mailcow. It's free, it's yours, and the hours are a hobby rather than a cost. Nothing below outweighs that.
A team, where mail stopping is somebody's problem. The question isn't whether you can run it — it's what happens when the person who can is on holiday. A hosted mailcow alternative removes the certificate renewals, the CVEs, the disk pressure and the blocklist entry you didn't cause, and adds what you'd otherwise build: DNS applied for you, bulk mailbox creation, setup invites so nobody hands passwords around, per-mailbox quotas and two-factor, and a shared mailbox with real membership.
Mail for clients. Now self-hosting means becoming a hosting company. You'd need per-client branding, provisioning at scale, verification, an interface in languages your clients' staff read, and an assistant able to drive it over MCP. That's a product, not a server, and building it is not a weekend.
Keep mailcow if you want to run a mail server. Take the alternative if you want to run something that merely depends on one.
Frequently Asked Questions
Is mailcow hard to install?
No — it's Docker Compose and the documentation is good. Installing was never the hard part. Operating it for three years, through upgrades and disk pressure and a blocklist entry you didn't cause, is the hard part.
How much RAM does mailcow need?
Their docs say 6 GiB plus 1 GiB swap for most private installations and 8 GiB for five to ten users. ClamAV and the full-text search engine are the memory-hungry components and both can be turned off.
Can I get good deliverability from a self-hosted server?
Yes, with correct SPF, DKIM, DMARC and PTR, a clean IP and patient warm-up. It's achievable and it isn't quick, and a single spam incident from one compromised account can undo months of it.
What about iRedMail, Mailu or Poste.io instead?
They're variations on the same trade. The stack differs, the operating burden and the IP reputation problem don't. Choosing between self-hosted options is a taste question; choosing whether to self-host at all is the decision that matters.
Can I move from mailcow without losing mail?
Yes. Mailcow speaks standard IMAP, so a migration is a normal mailbox copy driven from a CSV, with the result reconciled against the source afterwards so you can see what transferred.
Is a hosted mailcow alternative more expensive at scale?
Past a few thousand mailboxes, usually yes, and self-hosting wins. Below that, once you price your own hours honestly, hosted normally wins. Our plans cap counts by tier rather than charging per seat — up to 1,000 domains at 1,000 mailboxes each on Agency.
Do I keep server-side filters if I move?
Yes. Sieve is a standard, so your existing scripts have a direct equivalent and keep running at delivery on every device rather than in one client.
