Quickstart

Sign up at app.inbox.onesourcesoft.com. Free plan includes 3,000 emails per month forever, no credit card required.

From the dashboard go to Domains → Add Domain. Enter the domain you want to send from. The dashboard generates three CNAMEs:

mail.yourdomain.com           CNAME  mail.inbox.onesourcesoft.com
track.yourdomain.com          CNAME  track.mail.inbox.onesourcesoft.com
s1._domainkey.yourdomain.com  CNAME  s1._domainkey.<slug>.mail.inbox.onesourcesoft.com

Add these to your DNS provider. Verification polls every 30 seconds; most domains verify within five minutes.

Go to Settings → API Keys → Create. Give it a name and scopes. Copy the key — it is shown once.

curl -X POST https://api.inbox.onesourcesoft.com/api/v1/mail/send \
  -H "Authorization: Bearer $INBOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "personalizations": [{"to": [{"email": "you@yourdomain.com"}]}],
    "from": {"email": "hello@yourdomain.com"},
    "subject": "First email from Inbox OSS",
    "content": [{"type": "text/html", "value": "<h1>It works.</h1>"}]
  }'

Check the dashboard at Messages. You will see the full lifecycle: processed → delivered → opened (when you open the test email).

• Pick an SDK: Node, Python, Go, Ruby, PHP, Java, .NET, Rust.
• Add a webhook for real-time events: docs/webhooks.
• Migrate from SendGrid: two-line migration guide.