# AgentMail vs Brew: an inbox for your agent, or your agent running your email marketing

Canonical: https://brew.new/blog/agentmail-vs-brew
Author: Philip Sørensen
Published: 2026-10-13
Updated: 2026-10-13

Brew publishes this comparison. We reviewed AgentMail's own website, pricing page and documentation on October 12, 2026; this is a documentation comparison, not a claim of hands-on testing. Check current plan limits on AgentMail's pricing page.

You are building an AI agent and it needs email. Maybe it should answer support questions, chase invoices or book meetings. Maybe it should send your onboarding sequence and the monthly newsletter. Search "email for AI agents" and AgentMail comes up, and so does Brew.

Both give an agent email over MCP and an API. They solve different problems. AgentMail gives an agent its own inbox, so it can hold conversations. Brew gives an agent your company's customer email to run: it designs finished, on-brand emails, sends them to your audiences and runs the automations. Some teams need one. Plenty need both.

## Key takeaways

- AgentMail is an inbox API. Each agent gets its own address and can send, receive, thread and react to replies through webhooks or WebSockets.
- Brew is an email platform run by your agent. It designs on-brand emails from your brand, manages contacts and audiences, sends campaigns and runs lifecycle automations from your domain.
- AgentMail's docs focus on one-to-one conversations. Its deliverability advice favors plain, personal messages over designed marketing email.
- Brew has no conversational inbox for the agent. If the agent needs to read and answer replies, pair Brew with an inbox like AgentMail.

## What AgentMail is for

AgentMail describes itself as ["the first email provider built for AI agents"](https://docs.agentmail.to/). Its homepage calls it ["the email inbox API for AI agents"](https://agentmail.to/). The idea is that each agent gets its own email identity.

The core features, from its homepage and [documentation](https://docs.agentmail.to/llms.txt):

- Inboxes created on demand through a REST API.
- Sending and receiving with full threading.
- Webhooks and WebSockets for real-time events.
- Drafts for human review before a message goes out, plus labels to track state.
- Allow and block lists that control who each agent can email or hear from.
- Pods for keeping each customer's inboxes separate in a multi-tenant product.
- Custom domains with SPF, DKIM and DMARC, plus IMAP and SMTP access.
- Python and TypeScript SDKs, a CLI and a [hosted MCP server](https://docs.agentmail.to/integrations/mcp.md) for Claude, ChatGPT, Cursor and others.

AgentMail positions this against sending APIs. Its knowledge base says that ["unlike transactional email APIs that focus on one-way sending, AgentMail is built for two-way agent communication"](https://docs.agentmail.to/knowledge-base/what-is-agentmail.md). It also strips quoted history from replies and searches across all inboxes, which helps an agent that is reading mail all day.

[Pricing](https://www.agentmail.to/pricing) is by inboxes and volume. The free plan has 3 inboxes, 3,000 emails a month and 100 a day, without custom domains. Developer is $20 a month for 10 inboxes, 10,000 emails a month and 10 custom domains. Startup is $200 a month for 150 inboxes and 15,000 emails a day. Enterprise is custom.

AgentMail does this job well. If your agent has to act like a person with a mailbox, it is built for that.

## What AgentMail is not built for

AgentMail's documentation covers inboxes, messages and conversations. Its docs index has no pages on email design or templates, contact audiences, scheduled campaigns or unsubscribe management for subscribers. Its Lists feature is an allow and block list for an agent's inbox, not a mailing list.

Its own [deliverability guide](https://docs.agentmail.to/email-deliverability.md) points the same way. It tells you to start conversations, "not to close a sale in the first email". It warns that providers often flag emails that only include HTML. For volume, it suggests spreading sends across many inboxes rather than sending 10,000 emails from one.

That advice is sound for agent outreach and replies. It is the opposite of what a newsletter, a product launch or a designed onboarding sequence needs. Those emails go from one brand to many contacts, carry your layout and images, and need consent and unsubscribes handled for you. AgentMail's [terms](https://www.agentmail.to/legal/terms) also list "spam, phishing, or unsolicited messaging" as a prohibited use.

## What Brew is for

[Brew](/) is an AI-native email platform. Your agent connects to it over [MCP](/mcp), from Claude, ChatGPT, Cursor or Grok, and runs your company's customer email:

- It designs the email. Brew reads your website and brand files into an editable brand document, and the agent produces a finished email in your brand: layout, copy, images and footer. You can also edit it on a canvas.
- It manages contacts and audiences, with unlimited contacts on every plan.
- It sends campaigns and newsletters from your own verified domain.
- It builds and runs automations, such as onboarding, trial conversion and win-back, triggered by events from your product or tools like Stripe and Supabase. See [integrations](/browse/integrations) and the [flows gallery](/browse/flows).
- It sends transactional email, such as receipts and password resets, through a domain with a transactional sending purpose.
- It reports results, so the agent can check how a campaign did.

On OAuth connections, a call that emails people returns a confirmation request first, so you approve before a campaign goes out. Developers get the same surface through a REST API, a typed SDK and a CLI. The [MCP launch post](/blog/brew-mcp) explains how the connection works.

[Pricing](/pricing) is based on sends and AI credits. You can start free with 500 AI credits and 1,000 sends a month. Growth is $99 a month for 10,000 credits and 50,000 sends. Pro is $249 a month for 25,000 credits and 200,000 sends.

What Brew does not do: give your agent an inbox to read and reply from. Brew's documentation has no inbound email feature. If the agent needs to hold conversations, use an inbox product for that part.

## AgentMail vs Brew at a glance

| | AgentMail | Brew |
| --- | --- | --- |
| What it is | Inbox API for AI agents | Email platform your agent runs |
| Main job | Give an agent its own address to send, receive and reply | Design, send and automate your company's customer email |
| Receiving and threads | Yes, with webhooks and WebSockets | No inbound inbox |
| Email design | Not a design tool | On-brand emails generated from your brand |
| Contacts and audiences | Allow and block lists only | Yes, unlimited contacts |
| Campaigns and newsletters | None in its docs | Yes |
| Lifecycle automations | Build them in your own code | Yes, event-triggered flows |
| Transactional email | Sends through the API | Yes, through a transactional-purpose domain |
| Custom domains | Paid plans | Your own verified domain |
| MCP server | Yes | Yes |
| Pricing | By inboxes and volume; free plan, Developer $20/mo | By sends and AI credits; free to start, Growth $99/mo |

## Which one do you need?

Choose AgentMail if the agent is a participant in conversations. Support agents, sales assistants that reply to leads, agents that sign up for services or handle scheduling over email. The hard part there is receiving, threading and replying, and AgentMail handles that.

Choose Brew if the agent is running your email program. Newsletters, product announcements, onboarding and win-back sequences, receipts. The hard part there is making each email look like your brand, sending to the right audience and keeping automations running. Brew handles that.

## Using AgentMail and Brew together

The two fit together without overlap. A typical setup for a SaaS product:

1. Brew sends the designed lifecycle email: the welcome sequence, trial reminders and the monthly product update, from your marketing domain.
2. An agent with an AgentMail inbox, such as `support@` on its own subdomain, handles conversations. It answers questions, books calls and follows up.
3. When the support agent learns something useful, such as "this customer wants the annual plan", your code or the agent updates the existing contact in Brew, then fires the relevant event with `fire_trigger_event` and an `idempotency_key`. A published automation listening for that event runs the follow-up; updating a contact alone does not start it.

Keep each tool on its own domain or subdomain, so conversation mail and bulk marketing mail build separate reputations. Decide which system owns marketing consent. An unsubscribe in Brew does not reach an AgentMail inbox on its own.

## Frequently asked questions

### Is Brew an AgentMail alternative?

Only for part of the job. If you want your agent to send designed marketing and lifecycle email, Brew is the better fit. If you want your agent to have its own inbox and hold two-way conversations, Brew does not do that and AgentMail does.

### What is the best email for AI agents?

It depends on the job. For an agent that receives and replies to email, use an inbox API such as AgentMail. For an agent that runs your newsletters, campaigns and automations, use an email platform with an MCP server, such as Brew.

### Can an AI agent send marketing emails?

Yes, if it works through a platform built for marketing email. Connect the agent to Brew over MCP and it can design an on-brand campaign, pick an audience and send from your domain. On OAuth connections, Brew asks for your confirmation before anything goes out.

### Can I send newsletters with AgentMail?

AgentMail's docs do not describe newsletter features such as subscriber lists, templates or unsubscribe management. Its deliverability guidance is written for one-to-one conversations. Use a marketing platform for newsletters.

### Can I use AgentMail and Brew together?

Yes. Use AgentMail for the agent's inbox and conversations, and Brew for designed lifecycle and campaign email. Keep them on separate sending domains and pick one system as the owner of marketing consent.

## Next step

If your agent should be running your email program, [connect Brew over MCP](/mcp) and ask it to build your first onboarding sequence.