letterport vs AgentMail
Compared on 23 October 2026, from each company’s own pricing page
Both give AI agents real email inboxes over a REST API, webhooks and a hosted MCP server. letterport costs less per inbox on its paid plans and counts every recipient against hard caps. AgentMail has been around longer and offers more around the core: websockets, an SMTP relay, a SOC 2 report, team seats and enterprise options.
Plans side by side
| letterport | AgentMail | |
|---|---|---|
| Free | $0: 3 inboxes; 50 recipients a day, 1,000 a month; 3,000 received a month; 1 GB | $0: 3 inboxes; 100 emails a day, 3,000 a month; 3 GB |
| First paid plan | Developer, $19 a month: 25 inboxes; 1,000 recipients a day, 15,000 a month; 10 GB; 5 of your own domains | Developer, $20 a month: 10 inboxes; 1,000 emails a day, 10,000 a month; 10 GB; 10 custom domains |
| Next plan | Growth, $99 a month: 200 inboxes; 5,000 recipients a day, 100,000 a month; 50 GB; 50 of your own domains | Startup, $200 a month: 150 inboxes; 15,000 emails a day; unlimited storage; 150 custom domains |
| More than a plan holds | Hard caps: sending stops at the limit, nothing is billed | Add-ons: $2 a month per extra inbox, custom domain or 1,000 emails |
| Enterprise | Not offered yet | Custom: EU cloud, SSO, dedicated IPs, SLA |
letterport counts recipients (an email to three people counts three); AgentMail's page counts emails.
Features
| letterport | AgentMail | |
|---|---|---|
| REST API | Yes, with an OpenAPI description | Yes |
| Hosted MCP server | Yes: browser sign-in with chosen permissions, or an API key | Yes, on every plan |
| Webhooks | Yes, signed (Standard Webhooks), retried for about 24 hours | Yes |
| Websockets | No: webhooks or polling | Yes |
| SMTP relay | No | Yes |
| Your own domain | Developer and Growth; early access: receiving works, sending from your domain opens shortly | Paid plans |
| SOC 2 report | No | Startup and Enterprise |
Where letterport differs
- More inboxes for the money: 25 for $19 against 10 for $20; 200 for $99 against 150 for $200.
- Hard caps: nothing is ever billed for going over, and paying never loosens the mail rules.
- A delivery trail per recipient: queued, sent, then delivered, bounced or complained, where "delivered" means the receiving server said so.
-
Only the new text of a reply:
extracted_textdrops the quoted history, so an agent reads what the person just wrote. - Guardrails on by default: addresses that bounce or complain are suppressed, and high rates pause an account's sending.
Where AgentMail is ahead
- Websockets, so a local agent gets new mail without a public URL; and an SMTP relay.
- A SOC 2 report, team seats, and enterprise options such as an EU cloud, SSO and dedicated IPs.
- More free sending (100 emails a day against 50 recipients), and a longer track record: letterport is in early access.
Which to choose
Choose letterport if you want many inboxes on a small budget, hard spending caps, and per-recipient delivery you can show your users. Choose AgentMail if you need websockets, SMTP, a SOC 2 report or an enterprise contract today.
Prices change: check agentmail.to/pricing and letterport's pricing. If anything here is wrong, write to support@letterport.dev and we will correct it.
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