Resend for AI agents, now that it has inboxes
Resend launched Inboxes on 22 October 2026. Here is what that changes, and what still separates it from an API built for agents to sign up on their own.
Resend is no longer send-only: since 22 October 2026 its Inboxes give agents threaded mailboxes with search on your verified domain. Choose Resend if a human sets it up and you want threads, search and attachments. Choose Mailgi if agents must create their own addresses, receive more than they send, or keep mail longer than 30 days.
Mailgi vs Resend for agents
Resend is a superb sending platform that now also has mailboxes. The questions below are the ones that matter for an agent.
Last verified: 2026-10-31 against each vendor's own pricing and documentation pages. Pricing moves; re-check before you commit.
| Mailgi | Resend | |
|---|---|---|
| Who creates the account | The agent, with one POST | A human, then verifies a domain |
| Mailbox for each agent | Yes, on @mailgi.xyz or your domain | Inboxes on your verified domain (since 22 Oct 2026) |
| Inbox pricing | No per-inbox fee | 3 included, then $1 each on paid plans |
| Receiving | Free, not counted | Counts toward your sending quota |
| Retention | Kept until deleted; $0.25/GB-month above 10 MB | 30 days on standard plans |
| Threads / search | No / No | Yes / Yes (Inboxes) |
| Attachments | No | Yes |
| Sending price | $0.0005 per recipient, no plan | Free 3k/mo; Pro $20/mo for 50k |
| MCP server | Yes | Yes |
When Resend is the right call
Your app already sends through Resend
Adding Inboxes keeps one vendor, one domain setup and one bill.
Agents need threads, search or attachments
Resend Inboxes have all three; Mailgi has none yet.
You send at volume
Pro's 50,000 emails for $20 beats per-message pricing for steady volume.
When Mailgi fits better
The agent must get its own address unattended
No human signup, no domain verification to start: one POST on the shared domain.
Agents receive more than they send
Receiving is free on Mailgi and doesn't count against anything; on Resend it uses sending quota.
Mail must outlive 30 days
A Mailgi mailbox keeps mail until the agent deletes it.
Questions, answered
01Can Resend receive email for an AI agent?
Yes. Resend has had inbound since November 2025 and launched Inboxes, threaded mailboxes with folders, labels and search, on 22 October 2026. Inboxes need a verified domain, and received mail counts toward your sending quota.
02Can an AI agent create its own Resend account?
No. A human creates the Resend account and verifies a domain before any API key exists. Mailgi lets an agent register itself with one unauthenticated POST.
03Is Resend or Mailgi cheaper for an AI agent?
Resend is cheaper for steady sending volume (Pro is $20 for 50,000 emails). Mailgi is cheaper for agents that mostly receive or send little: no plan fee, free receiving, $0.0005 per external recipient and $0.02 once per new address.
One POST to start.
No signup form, no OAuth, no card to start. Receiving is free.
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