What a Mailbox Actually Costs on Your Own AWS
The real AWS bill for running your organization's mail server in your own account: instance, disk, IP, storage, snapshots, SES. About $20 a month for the whole org, and why I put that number on the pricing page.
Google and Microsoft charge per user and the infrastructure is invisible. inbox.camp charges per mailbox, with a ten-mailbox minimum, and the infrastructure is on your AWS bill, in plain sight. People ask what that bill is. Here it is, from my own organization's account, August 2026, us-east-1 on-demand prices.
The bill
| Item | What it is | Per month |
|---|---|---|
| EC2 t4g.small | The mail server. 2 vCPUs, 2 GB, ARM. Plenty for 5–50 mailboxes. | ≈ $12.30 |
| EBS 30 GB gp3 | The server's disk: mailbox index, config, spam model. | ≈ $2.40 |
| Elastic IP | A stable public address for your MX. | ≈ $3.65 |
| S3 | Every message body, versioned. $0.023 per GB. | $0.25 per 10 GB of mail |
| EBS snapshots | Hourly for two days, daily for a month. Incremental. | ≈ $1–2 |
| SES | Outbound mail. $0.10 per 1,000 messages. | ≈ $0 |
| Route 53 | Your hosted zone, which you probably already pay for. | $0.50 |
| Total | ≈ $18–22 |
That's for the whole organization, not per user. A 5-person team pays about $4 a head for the infrastructure; a 25-person team pays under a dollar. The instance and the IP are the fixed part; storage grows with mail, slowly, at S3 prices.
Where the mail actually lives
The number people expect to be big, storage, is the smallest line. That's because message bodies go to S3, not the server's disk. The disk holds only the index: which message is in which folder, flags, threads, search. A 100 GB organization needs maybe 10 GB of disk and $2.30 of S3. WorkMail's 50 GB per-user quota, which felt generous, costs about $1.15 per user per month to match in S3, and you don't pre-pay for it.
What you'd pay elsewhere
| 5 users | 15 users | 40 users | |
|---|---|---|---|
| Google Workspace Business Starter | $36–42 | $108–126 | $288–336 |
| Microsoft 365 Business Basic | $30–36 | $90–108 | $240–288 |
| WorkMail (until it closes) | $20 | $60 | $160 |
| inbox.camp + your AWS | $50 + ≈$20 | $75 + ≈$20 | $200 + ≈$22 |
At five seats you pay more than the big two, because of the ten-mailbox minimum; this is priced for teams, not for three people. At ten it's a wash. At fifteen you're cheaper than Google and level with Microsoft. At forty you're cheaper than either, and it isn't close. And unlike the big two, none of it is a mailbox you rent: the server, the bucket and the mail are yours, and they keep working if you stop paying us.
Why the number is on the pricing page
I could have hidden it. Most providers do; "$6/user" is a cleaner story than "$5 a mailbox plus about twenty dollars to Amazon." But the people leaving WorkMail chose AWS on purpose, can read a bill, and will see this one within a week. Better that the pricing page told them first.
Two honest caveats. Prices are on-demand; a one-year Savings Plan on the instance cuts it by roughly a third, and I'll help you set that up once you've decided to stay. And a large mailbox with years of attachments will push the S3 line up; it's still the cheapest line, but it isn't zero.