posta vs alternatives: mailboxes on your own domain, for people and AI agents

We compared posta with 32 email providers: inbox APIs for AI agents, test inbox tools, sending APIs, classic business email hosts, Turkish hosts and self-hosted servers. Facts come from each provider's official pricing and documentation pages, checked on 2026-10-11. Where a price could not be confirmed on an official page, we say so instead of guessing.

Short answer

• posta fits if you want real IMAP/SMTP mailboxes on your own domain, created with one API call; webhooks when mail arrives; code you can read and self-host (AGPL-3.0); flat yearly pricing instead of per-user monthly fees; or mail stored in Türkiye.
• Free plan: 1 domain, 1 mailbox, 500 MB, up to 50 outgoing messages a day, no card. Paid: Starter, 5 mailboxes for $50 a year; Pro, 10 mailboxes for $100 a year; storage on paid plans has no fixed limit (fair use). One-time card payment, no automatic renewal, 14-day full refund.
• posta is not the best fit if you need an office suite with calendar and documents, or high sending volume today.
• Bulk and newsletter sending: not on self-serve plans today. Need volume? Write to us; we set terms per customer.
• For AI agents: an open-source Python SDK and an MCP server, installed from GitHub (not on PyPI yet), plus the REST API, IMAP and SMTP.

All providers at a glance

Not stated means we could not find it on the provider's official page. Prices are as published, without tax unless noted.

AgentMail alternatives: email for AI agents

Services that let an agent get its own address and read or send mail through an API.

• AgentMail: The best-known inbox API for AI agents: Python/TypeScript SDKs, websockets, an MCP server and higher volumes. posta fits when you want your own domain on the free plan, flat yearly pricing, or code you can audit and self-host.
• Inbound: Open source (MIT) email API focused on receiving, parsing and replying in thread, with unlimited addresses on your domain. posta gives real IMAP/SMTP mailboxes and webmail, which Inbound's pricing page does not state.
• Nylas Agent Accounts: Email plus calendar identities for agents on a mature platform with SDKs, an MCP server and US/EU data regions. posta is simpler and cheaper per year, and open source.
• Hostinger Agentic Mail: Very low entry price inside Hostinger's business email, with webhooks on new mail. Its page lists full API access and MCP as upcoming; posta creates mailboxes by API today.
• Dead Simple Email: Agent inbox API with IMAP/SMTP credentials per inbox, SDKs in three languages and an MCP server. posta adds own domain on the free plan and an open-source codebase.
• OpenMail: EU-built agent inbox API with threading, attachment parsing and framework integrations. Pick it if you need EU hosting; posta stores mail in Türkiye.
• Bavimail: Covers transactional, marketing and inbound mail with a per-agent alias, driven by an MCP server. It is REST and webhooks only; posta gives real mailboxes you can also open in any mail app.

MailSlurp and Mailosaur alternatives: test inbox APIs

Programmable inboxes mainly for QA and automated tests.

• MailSlurp: Built for testing: disposable programmable inboxes, SMS, SDKs in many languages and a remote MCP server. posta is for long-lived mailboxes on your own domain at a lower yearly cost.
• Mailosaur: QA platform for capturing test email and SMS, with plugins for Cypress and other test tools. If you test sign-up flows, it is the specialist; posta is a real mailbox host.

Resend, Postmark, Mailgun, SendGrid, SES: a sending API is not a mailbox

These services send mail and can pass incoming mail to your code, but they don't give you mailboxes to log into. Many teams use one of them for app email and a mailbox host like posta for addresses people and agents actually read.

• Resend: Developer-friendly sending API with a receiving webhook and an MCP server. It sends and receives through code but has no mailboxes; use it for app email, and posta when you need an inbox people or agents can log into.
• Postmark: Strong deliverability for transactional email and a JSON webhook for inbound. No mailboxes; posta and Postmark solve different problems and work well together.
• Mailgun: Sending at volume, including bulk, with inbound routes that forward to your URL. No mailboxes.
• Twilio SendGrid: Large-scale sending and marketing email. Inbound Parse webhook is on Pro and above. No mailboxes.
• Amazon SES: The lowest cost per message at scale, if you already run on AWS and can wire receiving through S3, SNS or Lambda. No mailboxes.
• Cloudflare Email Service: Free forwarding and code-based handling of incoming mail if your domain is on Cloudflare. It routes mail; it does not store it in mailboxes.

Google Workspace, Microsoft 365 and Zoho alternatives: mailbox hosting on your own domain

Classic business email. Most charge per user per month with a fixed storage size per user.

• Google Workspace: Gmail with Docs, Drive, Meet and calendar for teams; 30 GB per user on Starter. Choose it when you need the office suite. posta is mail only, priced per year, not per user.
• Microsoft 365 / Exchange Online: Outlook and Exchange with 50–100 GB mailboxes and the wider Microsoft 365 suite. The standard for companies already on Microsoft.
• Zoho Mail: Generous free plan for small teams on their own domain, but IMAP/SMTP is paid. posta's free plan includes IMAP/SMTP and an API; Zoho's free plan allows more users.
• Proton Mail: End-to-end encryption and Swiss jurisdiction. Choose it when encryption matters most; posta gives standard IMAP/SMTP without a bridge app, plus an API.
• Fastmail: Polished, fast mail with calendar and contacts and 60 GB. A strong choice for people; posta is aimed at developers and agents who create mailboxes by API.
• Migadu: Flat pricing with unlimited mailboxes and domains; the cheapest plan sends 20 messages a day. The closest classic host to posta's model; posta adds a free plan and is open source.
• Purelymail: Very low flat price with no per-user fee and multiple domains. Marketing mail is not allowed. posta adds an API, webhooks and a free plan.
• iCloud+ custom domain: Cheap personal addresses on your domain if you already use Apple devices. Not built for business teams or automation.
• mailbox.org: Privacy-focused German provider with an office suite and German data centers.
• Infomaniak: Swiss provider with its own data centers and a broader collaboration suite.
• Titan: Business email sold mostly through hosting and domain partners; the price depends on the partner.
• Yandex 360: Mail, disk, calendar and video for companies under 250 staff.

Business email in Türkiye: Natro, Turhost, İsimTescil

Local hosts that keep mail in Türkiye, as posta does.

• Natro XMail: Turkish corporate email with 50 GB per account, mail kept in Türkiye and KVKK compliance stated. posta adds an API, webhooks, a free plan and open source.
• Turhost: Turkish corporate email with 50 GB per account on servers in Türkiye. Note the renewal price after the campaign year.
• İsimTescil HybridMail: Low-cost mail hosting from a large Turkish registrar, priced in USD with a one-year minimum.

Self-hosted open source: Stalwart and mailcow

Run your own mail server. posta's code is open too (AGPL-3.0), so you can self-host it.

• Stalwart: A modern all-in-one mail server you run yourself (IMAP, JMAP, SMTP, webmail). Choose it to operate your own server; posta is the hosted option, and its code is also open (AGPL-3.0).
• mailcow: Dockerized mail suite (Postfix, Dovecot, SOGo, Rspamd). posta itself runs on mailcow and adds the multi-tenant API, billing and panel on top.

Which one should you choose?

• You want an AI agent to get its own address on your domain and read or send mail: posta, AgentMail, Dead Simple Email or Nylas Agent Accounts.
• You want that, open source and self-hostable: posta (AGPL-3.0) or Inbound (MIT, receiving-focused).
• You only send app email (receipts, password resets): Resend, Postmark, Mailgun, SendGrid or Amazon SES.
• You test sign-up and email flows in CI: MailSlurp or Mailosaur.
• Your team needs calendar, documents and video too: Google Workspace or Microsoft 365.
• Encryption first: Proton Mail. Polished personal mail: Fastmail.
• Cheapest flat-price mailboxes for people: Purelymail or Migadu. Add an API and a free plan: posta.
• Mail must stay in Türkiye: posta, Natro or Turhost. Plus an API, a free plan and storage with no fixed limit on paid plans: posta.
• You want to run your own mail server: Stalwart, mailcow, or posta's open-source code.

Frequently asked questions

What is the cheapest way to get a mailbox on my own domain?

posta's free plan gives 1 domain and 1 mailbox with IMAP/SMTP at no cost. Zoho Mail's free plan allows up to 5 users on one domain but webmail only. For paid flat pricing, Purelymail starts at $10 a year and Migadu at $19 a year; posta Starter is $50 a year for 5 mailboxes.

Can an AI agent create its own email address?

Yes. With posta, one API call creates a real mailbox on your verified domain; the agent reads it over IMAP and sends with SMTP or the send endpoint, and a webhook tells you when mail arrives. AgentMail, Dead Simple Email, OpenMail and Nylas Agent Accounts offer similar inbox APIs.

Is there an open-source alternative to AgentMail?

posta is open source under AGPL-3.0 and can be self-hosted. Inbound is MIT-licensed and focused on receiving and replying. Stalwart and mailcow are open-source mail servers you run yourself.

Which email providers keep mail in Türkiye?

posta stores mail on servers in Türkiye, under Turkish law (KVKK). Natro and Turhost also state that mail is kept in Türkiye.

Are Resend, Postmark or Mailgun mailbox providers?

No. They are sending APIs that can also pass incoming mail to your code through a webhook or route. They do not give you mailboxes to log into with IMAP. Many teams use one of them together with a mailbox host.

Can I send newsletters with posta?

Not on the self-serve plans today. If you need bulk or newsletter sending, write to merhaba@preved.co and we set terms per customer.

How we compared

Every fact was read on 2026-10-11 from the provider's own pricing or documentation page; the provider name in the table links to that page. "Not stated" means we could not find it there, not that the feature is missing. Prices change; check the official page before you decide. We re-check this page every three months.

Found a mistake, or you run one of these services and something is out of date? Write to merhaba@preved.co and we will correct it. See also: posta vs AgentMail in detail · API documentation.