Receipts, password resets, OTPs, order confirmations — the mail people wait on with their finger on the refresh button. mailstein sends it from your own server and IP, fully authenticated, straight to the inbox. One API call, no per-contact tax, no shared-pool roulette.
Transactional email is a promise: the second someone clicks "send code" or checks out, the message is already on its way. mailstein is engineered around that promise — speed, authentication, and deliverability, on infrastructure you actually own.
Your API call returns fast and the message enters the Postal queue immediately — no batching window, no cross-tenant backlog ahead of your OTP. Time-sensitive mail is treated as time-sensitive mail.
Every domain you add is aligned automatically. mailstein generates the records, signs each message, and keeps DMARC passing — so a reset email is provably you, not a spoof the inbox provider quietly buries.
Dedicated IPs with managed warm-up mean your deliverability is yours — not dragged down by a stranger three tenants over in a shared SES pool. Bounces and complaints are suppressed automatically before they cost you.
Fire a receipt or an OTP with a single request over the REST API, the SDK, SMTP, or the CLI. mailstein signs it, routes it through your Postal MTA, applies suppressions, and streams every open, delivery, bounce, and complaint back to your webhooks — with full message logs living on your servers, not a vendor's.
A password reset is one email whether the user is on your list or not. mailstein charges for the send — never for the contact, never for a marketing "audience" you don't have. Transactional and broadcast live on the same platform and the same per-send meter.
Delivered, deferred, bounced, complained — each event is logged, queryable, and pushed to your webhooks in real time. When a customer swears the OTP never arrived, you can see the truth instead of guessing at a black box.
Self-hosted transactional email on your own IP — authenticated, observable, and billed per send. Start free with 50 emails a month and one domain. No card.
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