Fastmail vs Hosting Your Own Email: The Month Deliverability Becomes the Product

The first month of self-hosted mail is DNS and a green mail-tester score. The third month is the invoice that did not reach a client, the school that never saw the permission slip, and the Gmail user who found you in Spam after they had already “known” you for years. Deliverability became the product. Fastmail was selling that product the whole time. You were selling a compose file.

I left MSP ticket queues to run personal SMTP stacks. I still pay Fastmail for the address that has to work. I still run a box for the address that can fail. That split is the article. The search is Fastmail versus hosting your own. The honest unit of comparison is not IMAP features. It is the month you notice you are in the sender-reputation business.

What Fastmail is actually selling

Fastmail is IMAP, JMAP, a good web UI, masked emails, a company that has been off Google’s worst lists for a long time, and a support queue that has seen your PTR question before. You pay per user. You do not set SPF unless you want a custom domain, and when you do, they give you records that already match a warm infrastructure.

It is not magic. Fastmail can still land in Spam if you send like a list. It will not land in Spam because last night’s VPS neighbor sent pharmacy mail. That difference is the product. You are renting their reputation and their fight with Google. You are not renting ideology.

Alternatives in the same class: mailbox.org, Migadu, Proton if you accept their client story, Google Workspace if you are already in that religion. I name Fastmail because that is the search and because I have paid them long enough to be bored. The argument is “a host whose job is mail,” not a brand loyalty card.

What hosting your own is actually selling

Control, and the feeling of control. IMAP on your disk. Filters you can read. No “we have revised our AI scanning.” A domain that can move. Those are real. They are also not deliverability. Hosting your own sells a store and a protocol. Gmail sells a decision about whether you exist.

The first month you will believe the store is the hard part. Mailu, Mailcow, Mail-in-a-Box, Stalwart — pick one. Get DKIM aligned. Celebrate 10/10. Send to your own Gmail. It arrives. You tell a friend. The friend is not in your address book history. The friend does not arrive. You are now in a job you did not post: warming an IP, filing Postmaster Tools, arguing with Outlook, deciding whether to relay through SES and admit the SMTP you run is only half the product.

I have done that job for other people. It is a job. It is not a weekend. If your month three is “I am still tweaking Rspamd so my sister sees the mail,” you are a deliverability employee with one customer. Fastmail’s invoice is cheaper than your hours unless you enjoy the craft for its own sake.

The month it flips

It flips when a message that is not optional fails. A client. A government portal. A family medical form. Until then, self-hosting is a hobby with IMAP. After that, you either pay a sender or you become one.

Signs you have flipped:

• You are reading Google Postmaster and Microsoft SNDS on a Saturday.
• You have a spreadsheet of who uses Gmail and who uses Outlook.
• You added a relay “just for the important address” and now have two From identities to explain.
• You asked a recipient to whitelist you. Whitelists are not a product. They are a surrender.
• You delayed sending an invoice because “the IP is having a week.”

If those sentences are funny, stay on the box. If they are a calendar, pay Fastmail for the address on the invoice. Keep the box for newsletters to yourself, or stop the box.

What you lose when you pay

You lose the ability to grep the raw maildir on the metal without an IMAP client. You lose the ability to run a crazy Sieve you wrote at 1 a.m. without a UI. You lose the story you tell other homelab people. You accept that Fastmail can have an outage, a policy change, or a price change. Those are vendor risks. Self-hosting has operator risks. Month three is when people discover they preferred the vendor risk and were performing the operator one.

You also lose some privacy theater. Fastmail can see plaintext unless you do something inconvenient. Your own Dovecot can see plaintext too unless you do the same inconvenient thing. “I host so they cannot read it” is a sentence I only accept from people who also encrypt at rest with a key that is not on the same VM. Most self-hosters do not. Most Fastmail users do not. I would rather not pretend.

JMAP and Fastmail’s clients are excellent. That is a reason to pay if you are a power user of mail, not only a deliverability refugee. I should say that so this does not read as “Fastmail is only a reputation rental.” It is a good mail company. Reputation is why I pay them for the life domain. The client is why I do not mind.

A hybrid that is not a cop-out

Receive on your stack, send via a provider. Or: Fastmail as the MX, a local archive via IMAP sync. Or: Fastmail for humans, a self-hosted MTA for machines that send logs. The hybrid is how grown-ups admit two jobs exist. The cop-out is pretending the hobby MTA is the human inbox after month three went badly.

I do not like Fastmail as the only copy of mail I cannot lose. I pull IMAP to a disk I own. That is a backup conversation. It is not a reason to send from a dirty droplet. Sending is the reputation surface. Storing is the disk surface. Split them if you must be ideological and reliable at once.

Cost, honestly

Fastmail is a few dollars per user per month at personal scale. Self-hosting is a VPS, your time, and the invisible cost of a missed message. If you already rent the VPS for other things, the marginal money is small. The marginal time is not. I have spent more than a year of Fastmail fees in a single bad deliverability month — not in cash, in evenings.

Custom domains work on both sides. That is not a differentiator. Catch-all works on both sides and is a bad idea on both sides. Aliases are nicer in Fastmail’s UI. Sieve on your Dovecot is nicer if you like files. None of that matters in the month the product became reputation.

Families and “just one more mailbox”

Self-hosting looks cheaper at four family addresses until one teenager cannot get a reset SMS from a game and you become support. Fastmail’s family plans exist for this. So does “give the teenager Gmail and keep the adults on the host.” Mixed providers are allowed. Pride is not a topology. I have watched a household stay on a heroic Mail-in-a-Box because the domain felt like a project, while the kid used a Gmail the school already knew. The project did not include the kid. Fastmail would have. A paid host is allowed to be boring enough for children.

When I tell people to host anyway

Host if the mail is not to strangers, or if the strangers are on your own domain farm, or if you have a clean IP and a habit of reading logs, or if Fastmail’s jurisdiction or features are a hard no and you will pay the craft. Host if you are a mail person. Do not host to be a mail person. The lab is a harsh teacher and the students are your relatives.

Host a second domain for toys. Put the life domain on Fastmail. I have recommended that split more than I have recommended a heroic MTA. Heroism is a blog post. The life domain is a utility.

The comparison I wish the search used

Fastmail versus hosting your own is not Thunderbird settings. It is whether you want to be a mailbox vendor to Gmail. The month deliverability becomes the product, Fastmail (or mailbox.org, or Migadu) is the product you can buy. Your Docker stack is a store. Buy the product for the mail that must arrive. Keep the store if you still enjoy it. I enjoy it less than I used to, which is why I still run a stack and still pay a host. The ticket queue taught me which one pages me at 2 a.m. The host does not. The stack does, and it pages me about a problem Fastmail already staffed. I will keep both, and I will keep knowing which one is allowed to fail.