An AgentMail alternative, and when not to switch
AgentMail is the most complete email API for agents. Mailgi differs on one thing that matters to some builds: a program can register and send with no human at all.
Mailgi and AgentMail both give AI agents real mailboxes over an API. AgentMail is more mature, with threads, full-text search, IMAP, WebSockets and SOC 2. Mailgi lets an agent register itself and send immediately with no human and no wallet, has no per-inbox fee, and receives for free. Choose on that, not on a feature count.
Mailgi vs AgentMail, line by line
Facts from AgentMail's own pricing page and API docs.
Last verified: 2026-10-31 against each vendor's own pricing and documentation pages. Pricing moves; re-check before you commit.
| Mailgi | AgentMail | |
|---|---|---|
| Agent registers itself | Yes: one POST, can send immediately | Yes, but can't send until a human is attached; or pay per call from a USDC wallet ($2 per inbox) |
| Inbox pricing | No per-inbox fee | 3 free; 10 on $20/mo; 150 on $200/mo |
| Receiving | Free, not counted | Counts toward plan limits |
| Sending | $0.0005 per recipient, $0.02 once per new address | Included in plan: 3k/mo free, 10k/mo on $20 |
| Custom domains | Free on every agent | Paid plans (10 on $20/mo) |
| Threading | No (Re: subject only) | Yes |
| Search | No | Full-text |
| IMAP / SMTP / WebSocket | No / No / No | Yes / Yes / Yes |
| Webhooks | Yes, signed, no content | Yes |
| MCP server | Yes, hosted | Yes, hosted |
| Attachments | No | Yes |
| SOC 2 | No | Type II on $200/mo |
| Data location | Mail stored in Germany | US; EU on Enterprise |
Pick AgentMail if
You need threads, search or attachments now
We don't have them. AgentMail does, plus IMAP and WebSockets.
A human can sign up once
Then our main difference doesn't apply to you, and AgentMail is the more mature product.
You need a SOC 2 report
AgentMail has a Type II report on its $200 plan. We don't have one.
You send high, steady volume to new people
At 10,000 first-contact emails a month AgentMail's $20 plan is far cheaper than our $0.02 introduction charge. Mailgi is not built for outreach.
Pick Mailgi if
The agent has to create its own address, unattended
One POST, no human, no wallet, and it can send straight away. That is the reason Mailgi exists.
You run many agents with little traffic each
No per-inbox fee and free receiving: a thousand mostly idle agents cost nothing until they send.
Most mail goes to people who wrote first
Anyone whose DKIM-signed mail reached the agent is a known contact; replying costs $0.0005.
You want your own domain on day one, free
Custom domains are free and every agent on them shares the organisation's balance.
Questions, answered
01What is the best AgentMail alternative?
It depends on why you're leaving. For agents that register themselves with no human, Mailgi. For a team already on Resend, Resend Inboxes. For mailbox plus calendar, Nylas Agent Accounts. If you need threads, search and SOC 2, AgentMail itself is still the strongest option.
02Can an AgentMail agent sign itself up without a human?
Partly. AgentMail's sign-up endpoint now makes the human email optional, but without one the inbox can only receive until a human is attached. An agent with a USDC wallet can instead pay per request over x402, $2 per inbox; AgentMail's docs don't say what such an inbox may send to.
03Is Mailgi cheaper than AgentMail?
For many agents with light traffic, yes: no monthly fee, no per-inbox fee and free receiving. For steady volume to new recipients, no: AgentMail's $20 plan includes 10,000 emails, while Mailgi charges $0.02 the first time an agent writes to each new address.
04Can I move from AgentMail to Mailgi?
Yes, but it is a rewrite of the mail calls, not a config change: Mailgi has its own REST API, SDK and MCP server, and no threading or search. Register a Mailgi agent per AgentMail inbox and point your domain's MX records at Mailgi when you are ready.
One POST to start.
No signup form, no OAuth, no card to start. Receiving is free.
Open the dashboard →