AI agents
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- 17 Oct 2026
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AI agents
What an email inbox for an AI agent costs in 2026
List prices for a seat, a shared mailbox, an email API for agents and a do-it-yourself build, and the costs that aren't on any price list.
5 min read · 17 Oct 2026 · 6 sections
On this page 6 sections
- What does each option cost?
- What does each option include?
- What costs aren’t on the price list?
- Which one fits?
- What does it cost on SuperMailOS?
- Questions
- Is there a free email inbox for AI agents?
- Does an AI agent need a paid seat?
- How much does AgentMail cost?
- What's the cheapest way to give 25 agents email?
At list prices, a Google Workspace or Microsoft 365 seat costs $7 to $8.40 a month for each agent, and a Microsoft 365 shared mailbox nothing extra if you already pay for Microsoft 365. Email APIs built for agents start free for three inboxes and charge $15 to $27 a month for ten. Building your own on a sending service costs cents per thousand emails, plus the build. On SuperMailOS, agent inboxes come with your team’s seats. The bigger costs aren’t on any price list: building what keeps an agent from emailing the wrong people, and the damage when it does.
What does each option cost?
A month, at each provider’s list price:
| Option | 1 agent | 10 agents | 25 agents |
|---|---|---|---|
| Google Workspace Business Starter, a seat per agent | $7 on the yearly plan, $8.40 flexible | $70 on the yearly plan, $84 flexible | $175 on the yearly plan, $210 flexible |
| Microsoft 365 Business Basic, a seat per agent | $7 | $70 | $175 |
| Microsoft 365 shared mailboxes | Nothing extra with a Microsoft 365 subscription, up to 50 GB each | ||
| AgentMail | Free on its domain, or $20 (Developer) on yours | $20 (Developer) | $50 (Developer plus 15 extra inboxes) |
| Nylas Agent Accounts | Free on a trial domain, or $15 (Essentials) on yours | $15 (Essentials) | $49 (Pro) |
| Resend inboxes | Free on your domain, up to 100 emails a day | $27 (Pro plus 7 extra inboxes), 50,000 emails a month | $42 (Pro plus 22 extra inboxes), 50,000 emails a month |
| Your own build on Amazon SES | $0.10 per 1,000 emails received (plus $0.09 per 1,000 chunks of 256 KB) and $0.10 to $0.16 per 1,000 sent, plus storage, servers and the build | ||
| Your own build on Cloudflare | Receiving free; sending $0.35 per 1,000 past 3,000 a month on Workers Paid (from $5 a month), in beta, plus the build | ||
| SuperMailOS, agent inboxes included with seats | $4 (1 Pro seat; $3 billed yearly) | $12 (2 Business seats; $10 billed yearly) | $30 (5 Business seats; $25 billed yearly) |
Google Workspace facts from Google Workspace’s own pages: Google Workspace pricing, Google Workspace plans, Google: email aliases, Google: multiple domains · checked 14 Oct 2026
Microsoft 365 facts from Microsoft 365’s own pages: Microsoft 365 pricing, Microsoft: email aliases, Microsoft: shared mailboxes, Microsoft: domains FAQ · checked 14 Oct 2026
AgentMail facts from AgentMail’s own pages: AgentMail pricing, AgentMail: what it is, AgentMail: human-in-the-loop, AgentMail: Agent Armor, AgentMail: API reference, AgentMail: docs index · checked 16 Oct 2026
Nylas facts from Nylas’s own pages: Nylas pricing · checked 17 Oct 2026
Resend facts from Resend’s own pages: Resend pricing · checked 17 Oct 2026
Amazon SES facts from Amazon SES’s own pages: Amazon SES pricing · checked 17 Oct 2026
Cloudflare facts from Cloudflare’s own pages: Cloudflare pricing, Cloudflare Workers pricing · checked 17 Oct 2026
The rows don’t buy the same thing. A Google Workspace or Microsoft 365 seat is a full account with office apps. The agent email APIs are built for developers, and most count every email sent and received against a monthly allowance. A SuperMailOS seat is a person’s mailbox, and the agent inboxes come with it: 2 per seat on Pro and 5 on Business.
What does each option include?
A seat at Google Workspace or Microsoft 365. A complete account, which is more than an agent needs, billed per user. Software usually reaches it through the Gmail API or Microsoft Graph, and the broad versions of that access can reach every mailbox in the company unless an admin narrows it (how to give an agent its own address). Approval before sending isn’t built in.
A Microsoft 365 shared mailbox. No license needed up to 50 GB, if you already pay for Microsoft 365. It isn’t meant to be signed in to, so the agent gets in through an app registration that an admin limits to that one mailbox. Cheap in money, not in setup.
An email API built for agents: AgentMail, Nylas or Resend. Inboxes created over an API, with webhooks, and a free start. Built for developers and the products they ship. Your own team’s email lives somewhere else, and rules like approval before sending are mostly yours to build.
Your own build on Amazon SES or Cloudflare. Email in and out costs very little per thousand messages. Everything else is yours to build and run: storing mail, threading conversations, approvals, holding spoofed mail back, a screen where people can see what the agent did, and handling bounces and complaints.
Agent inboxes in your business email. On SuperMailOS, an agent’s inbox sits next to your team’s, on your own domain, with approval for new recipients, held spoofs and the AI line built in. It’s for your own team’s agents, not for handing out inboxes to your product’s users.
What costs aren’t on the price list?
- The guardrails. Approval for new recipients, daily limits, holding spoofed mail and removing hidden text are real engineering work, and they have to keep working as attackers change tactics. Where an option doesn’t include them, budget for building them (human-in-the-loop email, prompt injection by email).
- Your domain’s reputation. Spam complaints about an agent’s email count against the domain it sends from, often the one your whole team uses (should an agent send from your own domain?).
- Mistakes. An email can’t be unsent. One that reaches the wrong person can cost more than any plan in the table.
- Compliance. Saying the email came from an AI where the law asks for it, and the usual rules for commercial email (do AI-written emails need to say so?).
Which one fits?
- You’re building a product that hands out inboxes to its users: an email API built for agents.
- You run Microsoft 365 and have an admin with time: a shared mailbox, with the app’s access limited to it.
- You have engineers and want full control: your own build on a sending service.
- Your team wants agents working next to it, on your domain: agent inboxes in your business email.
What does it cost on SuperMailOS?
Agent inboxes never take a seat. Each Pro seat ($4 a month, or $3 billed yearly) includes 2, and each Business seat ($6, or $5 yearly) includes 5. The 14-day trial includes 3, with no card. Every seat is also a mailbox for a person on your team. The AI agent inboxes page has the rest, and SuperMailOS vs AgentMail a side-by-side.
Questions
Is there a free email inbox for AI agents?
A few, with limits. AgentMail's free plan has 3 inboxes on its own domain, with a "Sent via AgentMail" footer. Nylas's has 3 Agent Accounts on a Nylas trial domain. Resend's has 3 inboxes and 3,000 emails a month, at most 100 a day. SuperMailOS has a 14-day free trial that includes 3 agent inboxes.
Does an AI agent need a paid seat?
At Google Workspace and Microsoft 365, a user account needs a license, so an agent with its own account takes a seat. A Microsoft 365 shared mailbox doesn't, up to 50 GB. On SuperMailOS, agent inboxes never take a seat: they come with your people's seats.
How much does AgentMail cost?
From its pricing page: Free for 3 inboxes, Developer at $20 a month for 10, extra inboxes at $2 a month each, and higher plans for more.
What's the cheapest way to give 25 agents email?
On list price alone, shared mailboxes if you already run Microsoft 365, or a build of your own on a sending service, if you count your time as free. Among ready-made options, $42 a month on Resend, $49 on Nylas and $50 on AgentMail. On SuperMailOS it's $30 a month for 5 Business seats, which also give five people their own mailboxes.