Sign in, verify a domain, mint an API key, and send. mailstein handles SPF, DKIM, DMARC, and IP warm-up for you — so your mail lands from your own infrastructure, not a shared SES pool.
No credit card required. The free plan gives you 50 emails a month and one domain — enough to wire up your app end to end before you scale.
Sign in at app.mailstein.com and you land in a fresh workspace. Your logs, contacts, and reputation live here — on your own infrastructure, not rented from a third party.
Enter your sending domain and mailstein generates the exact SPF, DKIM, and DMARC records. Drop them into your DNS, click verify, and you are authenticated to send.
Generate a scoped key for your environment. Use it as a Bearer token for the REST API, or as SMTP credentials — same key, same suppression and analytics behind both.
One POST and you are live. mailstein signs the message with DKIM, routes it through your dedicated IP, and records the result in your message log — opens, clicks, bounces, and complaints all tracked automatically.
Prefer SMTP? Point your existing mailer at smtp.mailstein.com on port 587 with your API key as the username and password. No code change beyond the connection string.
The same domain and API key power transactional receipts and password resets as well as broadcast newsletters and campaigns. Everything is billed per send — never per contact.
Receipts, verification codes, alerts. Sub-second delivery through your warmed IP, with webhooks for every delivery, open, and bounce so your app knows what happened.
Import contacts, build audiences, and send broadcasts from the same dashboard. Suppression lists are shared across both, so a complaint on a newsletter protects your transactional stream too.
Add a domain, grab a key, and send — free, no card, on infrastructure that stays yours.
Start free →