---
title: "AgentMail alternative"
description: "How Unitpost compares to AgentMail — pricing, free tier, API design, and where AgentMail is still the better choice."
url: https://www.unitpost.com/alternatives/agentmail
section: Alternatives
updated: 2026-11-02
---
# AgentMail alternative

## Unitpost vs AgentMail

> An email API for AI agents: each agent gets its own inbox, created by API, for two-way threaded conversations rather than one-way notifications.

**AgentMail free tier:** 3 inboxes, 3,000 emails a month (100 a day), no custom domains, with a "Sent via AgentMail" footer

**AgentMail pricing shape:** Priced by inboxes, domains and sends: Developer is $20 a month for 10 inboxes and 10,000 emails, with add-ons per inbox, domain or 1,000 emails.

## What AgentMail does well

- Inboxes created by API, thousands at a time, each with its own address
- Threads, reply and reply-all built in, with the new text extracted from quoted history
- Inbound pushed over WebSockets, so an agent needs no public webhook URL
- A hosted MCP server with OAuth and 47 tools, including drafts and calendars
- Inbound prompt-injection scanning (Agent Armor) and per-tenant isolation (Pods)

## Choose AgentMail if

- Each agent needs its own mailbox and two-way threads, more than you need to send to a customer list
- You create inboxes per user or per tenant at scale
- You want inbound mail over WebSockets without a public endpoint

## Choose Unitpost if

- Your agent sends your product's mail to your users: receipts, resets, notifications and campaigns
- You want a free plan without a footer, on your own domain
- You want marketing email, templates and SMS on the same contacts and bill
- You want every agent send to pass the same checks as the API: verified domain, suppressions, topics and approval

## Feature comparison

| Capability | Unitpost | AgentMail |
| --- | --- | --- |
| What it's built for | An app's email and SMS to its users, with agents as one more client | Mailboxes for agents: create, receive, thread and reply |
| Free plan | 5,000 emails/month, 200/day, no credit card | 3 inboxes and 3,000 emails a month, 100 a day, no custom domains, with a footer |
| Receiving and threads | Receiving on your verified domain, with replies threaded by in_reply_to | Inboxes and threads as API resources, with reply, reply-all and forward |
| Marketing email and templates | Campaigns, segments, topics and templates | Not offered |
| SMS | On paid plans, on the same contacts and key | Not offered |
| MCP server | Hosted, OAuth, one tool per API operation, every send through the sending gate | Hosted, OAuth or API key, 47 tools |
| Idempotency keys on send | Idempotency-Key on sends, 24-hour dedupe window | Idempotency-Key on sends, replies and forwards, kept 24 hours |
| Dedicated IPs | Not launched yet | Enterprise, through sales |

## How do I switch from AgentMail?

There is no one-key importer for AgentMail: export your contacts and suppressions, import them, verify your sending domain, and move one kind of mail at a time.

Inboxes map to addresses on a verified domain with receiving turned on: replies reach your webhook as email.received, and the agent answers with in_reply_to to stay in the thread.

## FAQ

### Is Unitpost an AgentMail alternative?

For agents that send your product's email to your users, yes: one API for transactional, marketing and SMS, with every agent send checked like any other. If each agent needs its own mailbox with threads and inbound over WebSockets, AgentMail is built for exactly that.

### Can an agent receive and reply to email on Unitpost?

Yes, on your own domain: turn on receiving for a verified domain, subscribe a webhook to email.received, read the message over the API, and reply with in_reply_to so mail clients thread it.

## Related

- [Twilio SMS alternative](https://www.unitpost.com/alternatives/twilio): How Unitpost compares to Twilio for SMS — per-country pricing, sender registration, compliance, and where Twilio is still the better choice.
- [Telnyx SMS alternative](https://www.unitpost.com/alternatives/telnyx): How Unitpost compares to Telnyx for SMS — per-country pricing, sender registration, compliance, and where Telnyx is still the better choice.
- [Bird SMS alternative](https://www.unitpost.com/alternatives/bird): How Unitpost compares to Bird for SMS — per-country pricing, sender registration, compliance, and where Bird is still the better choice.