openagent.email
A fit when you want open-source control, your own domain and infrastructure, and persistent agent mailboxes.
openagent.email vs AgentMail vs MailSlurp
This page compares three ways to give agents email: openagent.email is Apache-2.0 software you run yourself; AgentMail is a managed agent-email product with enterprise AWS Outposts BYOC; MailSlurp is a hosted platform for testing email and SMS.
Who should pick which?
Fit notes from the facts on this page, not universal recommendations.
AgentMail
A fit when you prefer managed agent email. Enterprise AWS Outposts BYOC is the existing option when mail content must stay in your AWS account; the vendor still runs the product control plane.
MailSlurp
A fit when you primarily test application email and SMS flows and do not want to operate mail infrastructure.
| openagent.email | AgentMail | MailSlurp | |
|---|---|---|---|
| Open source | Apache-2.0 | Closed source | Closed source |
| Deployment | Any VPS or cloud | SaaS or AWS Outposts BYOC | SaaS only |
| Price | Free software + your server; no per-inbox fee | Developer/Startup: PAYG +$2 per inbox, domain, or 1k sends; annual plans save 20% | Capped plans + metered overages |
| Unlimited inboxes | Yes, on your domain | Paid-tier limits | Paid-tier limits |
| MCP-native | Yes | Official MCP and plugin ecosystem | Official hosted MCP |
| Plugins/ecosystem | Universal MCP: connect directly from Claude, ChatGPT, Grok, or Cursor; official connection guide | Official OpenClaw plugin + Grok Bot Cursor plugin + official Codex plugin | Official MCP setup guides for Claude Code, Cursor, Codex, and Gemini CLI |
| OTP/link extraction | Built in | Not independently verified | Testing workflows |
| Mail data residency | Your box | SaaS: theirs; Outposts: your AWS | Their infrastructure |
| Vendor control plane | None | Yes, including Outposts | Yes |
| You run a server | Yes | No, unless enterprise BYOC | No |
Last checked: AgentMail 2026-08-30 · MailSlurp 2026-09-03. AgentMail sources: pricing, official MCP docs, official OpenClaw plugin, Grok Bot email / Cursor plugin, official Codex plugin, 19 Aug 2026 outbound incident. MailSlurp sources: pricing, official MCP docs.
AgentMail's 19 August 2026 incident page states that outbound sending was disrupted for about eight hours after AWS paused sending on shared email infrastructure. That is AgentMail's own account; no further claim is made here.
Open source
Source availability determines whether you can audit, fork, and keep running the system. openagent.email is Apache-2.0 software with standard SMTP/IMAP underneath. AgentMail and MailSlurp are closed-source hosted products. The trade-off is simple: a managed vendor removes operations; open source leaves the operating choice with you.
Deployment
openagent.email runs on any VPS or cloud you choose. AgentMail is hosted SaaS by default, with an enterprise Outposts BYOC option that runs send, receive, storage, and search in your AWS account (AWS today; more clouds planned). MailSlurp is SaaS only. If you never want to operate a server, hosted is the fastest path; self-hosting trades that convenience for portability.
Price
openagent.email is free software: a small VPS from about $5/month and a domain cover the infrastructure, with no per-inbox fee. AgentMail's Developer and Startup plans add PAYG at $2 per inbox, domain, or 1k sends, and annual plans save 20%; Outposts is enterprise-tier. MailSlurp meters inboxes and volume. Hosted pricing buys operational convenience, while a fixed server bill is usually easier to predict for many persistent identities.
Unlimited inboxes
One openagent.email domain can hold unlimited persistent anything@yourdomain identities without provisioning or per-inbox cost. AgentMail's capacity depends on its paid tier, and so does MailSlurp's. Persistent production mailboxes for agents and inboxes used to test an application are useful for different jobs.
MCP-native access
openagent.email includes a REST API, MCP server, and a human dashboard. AgentMail has an official MCP and plugin ecosystem. The deployment and control-plane distinction is that openagent.email is Apache-2.0 software you self-host on any VPS or cloud, with no vendor control plane and unlimited identities on your own domains. MailSlurp offers an official hosted MCP, REST, language SDKs, and a dashboard. The practical difference is not whether an API exists, but whether your agent's primary workflow is mailbox work or testing an application you are building.
OTP and verification links
openagent.email automatically extracts OTP codes and verification links while keeping raw text and HTML available. The earlier AgentMail comparison did not independently verify an equivalent extraction feature, so it makes no claim here. MailSlurp is specifically geared to exercising an app's email and SMS flows, and it offers SMS testing, which openagent.email does not.
Mail data residency
Your openagent.email mail and tokens stay on your machine. AgentMail Outposts is a real option when email content must stay in AWS, but AgentMail Cloud still operates its dashboard, authentication, billing, upgrades, and product control plane. MailSlurp stores mail in its hosted infrastructure. Residency is a meaningful distinction, but it is not identical to owning the whole stack.
Vendor control plane
openagent.email has no vendor control plane: you run the dashboard, auth, upgrades, and mail system. Managed products own those operational pieces, including uptime and deliverability. That is valuable when you want a vendor accountable for operations; it is also the dependency you avoid when you self-host.
You run a server
Self-hosting means you own DNS, the machine, and its reputation. In return, you get an auditable stack and can use Amazon SES or another SMTP relay with one environment variable if your VPS provider blocks port 25. AgentMail is the better fit when that is not work you want; MailSlurp is the better fit for CI/QA and zero-infrastructure test inboxes.
AgentMail: deployment and control, in detail
AgentMail's enterprise Outposts BYOC option has real AWS data residency. It is not the same as open-source self-hosting, because the AgentMail product control plane remains operated by the vendor. That may be exactly the trade-off an enterprise team wants.
Fair credit where it is due: Outposts is a real option when email content must stay in AWS. If you want zero servers, AgentMail's managed path is the fastest one.
Agent workflows beyond the mailbox
openagent.email includes a REST API, MCP server, and a human dashboard. AgentMail offers REST, websockets, webhooks, and SDKs; MailSlurp offers an official hosted MCP, REST, language SDKs, and a dashboard. openagent.email automatically extracts OTP codes and verification links while keeping raw text and HTML available. It also has email-backed agent-to-agent task threads with server-stamped states, notification delivery for external agent activation, a dashboard work-order view, an A2A-vocabulary Agent Card, and per-identity ntfy push tiers: interrupt only, sender + subject, or body + OTP, set by an admin. Equivalent task and push features were not verified for the other products, so no claim is made.
FAQ
What is the core difference?
openagent.email is Apache-2.0 software you run on any VPS or cloud. AgentMail is a managed agent-email product: SaaS by default, with enterprise AWS Outposts BYOC. MailSlurp is a hosted platform for testing application email and SMS.
Is openagent.email free and open source?
Yes. It is Apache-2.0 software with no per-inbox fee. You pay for your own server and domain; a small VPS from about $5/month plus a domain covers the infrastructure.
Does AgentMail have BYOC?
Yes. AgentMail's enterprise Outposts BYOC option runs send, receive, storage, and search in your AWS account. AgentMail Cloud still operates the dashboard, authentication, billing, upgrades, and product control plane.
When is MailSlurp the better fit?
When you primarily need to test application email and SMS flows without operating mail infrastructure. MailSlurp is SaaS only and offers SMS testing, which openagent.email does not.
Can an agent connect by MCP or API?
Yes. openagent.email includes a REST API and an MCP server. AgentMail has an official MCP and plugin ecosystem. MailSlurp offers an official hosted MCP, REST, language SDKs, and a dashboard.