Changelog
What we shipped, newest first, written for the people using it. Dates are when the change was committed; the beta runs everything free while we build.
Updated 4 min read
Follow along with the RSS feed. For how each feature works today, the docs are the reference; this page is the history.
Entries
Integrations, alternatives and an SMTP error reference
Four integrations, each run end to end before we wrote it up: Claude Code and Cursor over MCP, Playwright with catch-all test addresses, and Python with plain requests.
Pages for people moving from AgentMail, Mailosaur and Resend, with when to stay and how to move, and an SMTP error code reference with real sessions against our own servers.
A free email deliverability test
Send one message to a one time address and get a report on it: SPF, DKIM and DMARC, spam scoring rule by rule, and what to fix, kept for 7 days. Try the email deliverability test; bounce codes it helps explain include 550 5.7.26.
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Batch and scheduled sends, and a Node SDK
POST /v1/emails/batchsends up to 100 emails in one request, with strict or permissive validation.scheduled_atholds an email for up to 30 days, and it can be rescheduled or canceled; both work as in Resend. See the Emails API. A Node and edge SDK is written and documented, and coming to npm.857063d 86de431 1ae3008 6602650
Sending pauses on high bounce or complaint rates
Mailbay sends from shared IPs, so a workspace whose mail hurts their reputation now pauses: over 24 hours and at least 50 recipients, when hard bounces reach 5% (and at least 3) or complaints reach 0.1% (and at least 3). Sends then fail with
sending_pausedand the reason, the owner gets one email and the dashboard shows a banner. Receiving keeps working. Details under automatic pause.d9bae09 8ca3fb5 3abca31
A lighter, faster website
The site header is rendered on the server, fonts load with the first paint, and the docs menu on phones is a native dialog, so pages ship less JavaScript.
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Private beta with a waitlist
Sign ups go through a waitlist while we invite people in small batches. Everything is free during the beta.
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Comparisons, use case guides and the blog
Sourced comparisons with five other email APIs, step by step use case guides, and the first blog posts.
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A sending sandbox until you verify a domain
Without a verified domain, inboxes send to the people in your workspace, your own addresses and the test addresses only; anything else fails with
sandbox_recipient_not_allowed. Verify a domain to email anyone. See the free sandbox.cba6f31
A private mailbay.email address space with a Catch-all
Every workspace gets its own code on
mailbay.email. Any address under it reaches the Catch-all, so agents and tests can use a fresh address without creating an inbox. See your address space.2f0dc1e
Retention, export and deletion
Set how long a workspace keeps mail, export a workspace's data, or delete it, from the settings page. By default mail is kept until you delete it.
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IMAP and SMTP for mail apps
Read an inbox in Apple Mail or Outlook over IMAP with an app password, and send as that inbox over SMTP. Apps can also send over SMTP on ports 587 and 465 with an API key as the password; bad credentials get 535 5.7.8 with what to use instead.
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A shared support inbox
One inbox across projects for support@ and friends: assign, close and snooze conversations, live updates, keyboard shortcuts, and forwarding to an address you confirm.
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One click DNS setup
For DNS providers that support Domain Connect, Mailbay can add a domain's records in one click. Other domains get the records to copy, each checked live. See one click setup.
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Members, roles and an audit log
Invite teammates with a role, limit them to certain inboxes, and see who did what in the audit log, with dates and IP addresses.
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Projects and the paste your domain wizard
Group domains, inboxes and keys by project. The add project wizard reads your domain's DNS, keeps the mail you already receive, and merges our SPF and DMARC into your existing records instead of replacing them.
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A Resend shaped send endpoint
POST /v1/emailsaccepts the same request body as Resend's send API, so moving is a base URL and a key. See the Resend alternative page for what is and is not supported.eec2406
Plans and usage
GET /v1/planslists the plans andGET /v1/meshows what you have used. The free plan is 3 inboxes, 3,000 emails a month and 3 domains; Pro is planned at $9 a month. Billing is not live yet; see pricing.f93ee34 5d27bae
Email sign in and API keys
Sign in with a magic link or a code sent to your email, and manage API keys in the dashboard or with
mailbay keys. Key secrets are shown once and stored hashed.85fa317 2ff05a5
Inboxes, sending, domains and events
The first version: a REST API and
mailbayCLI for inboxes, messages and threads; a wait that returns one time codes; sending through our own mail servers with replies, suppressions and idempotency; custom domains with DKIM and live DNS checks; signed webhooks and a WebSocket stream; and incoming mail scored for spam with SPF, DKIM and DMARC results on every message.f081da7 e9c666c 71a11ef 455843e 6b49b86 89f9c16 68f8318
An MCP server for agents
Tools to create inboxes, send, reply, read and wait for email, add domains and create webhooks, for Claude, Cursor and any MCP client, with an API key. See the MCP docs.
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Read next
Join the beta
Mailbay is in private beta and free while the beta runs: inboxes, sending, your own domains and MCP. We invite people in small batches and read every note on the form.