Transactional Email Service & API for High-Inbox Delivery
Send OTPs, password resets, receipts and order confirmations that land in the inbox — over a REST Email API or SMTP relay with SPF, DKIM and DMARC authentication, dedicated IPs and real-time delivery events. Trusted across India and 190+ countries.
What is a transactional email?
A transactional email is a message triggered by a user action or account event — an OTP, password reset, order confirmation, receipt or shipping alert. It is expected, sent one-to-one, and time-sensitive, which is why it must reach the inbox in seconds rather than a promotions tab or spam folder.
That makes it very different from marketing email, which is broadcast to a list to promote offers. Transactional email carries no promotional content, needs no unsubscribe by law in most cases, and travels on high-reputation infrastructure so that critical messages like OTPs and invoices are never delayed. For campaign sends, use our promotional / marketing email API instead.
Two ways to send: REST Email API or SMTP relay
Fire a single HTTPS request from any language, or point your existing application at our SMTP relay — both routes share the same deliverability, tracking and suppression engine.
REST Email API
Send a JSON payload over HTTPS with a Bearer token — ideal for cleanly separating sending logic, templates and dynamic data at scale. Get structured responses with a message ID for tracking.
SMTP relay
Swap your current SMTP host for our relay with a username, password and port. No code rewrite — perfect for existing apps, CMS platforms and off-the-shelf software.
Email API vs SMTP relay
Both deliver to the inbox with the same reputation — the right choice depends on your stack and how much control you need.
| Dimension | Email API | SMTP Relay |
|---|---|---|
| Integration effort | Call a REST endpoint from your code | Change SMTP host, port and credentials |
| Best for | New apps, high volume, fine-grained control | Existing apps, CMS and legacy software |
| Speed / latency | Lowest latency, async queueing | Fast, adds SMTP handshake overhead |
| Templates & dynamic data | Full template IDs and variables in the payload | Templating handled by your application |
| Batch / bulk | Batch many recipients in one request | One message per SMTP transaction |
| Event data & webhooks | Rich JSON events and message IDs | Events via dashboard and webhooks |
| Language support | Any language with an HTTP client | Any platform with an SMTP library |
| Setup time | Minutes with an API key | Minutes with relay credentials |
Sending high volume newsletters instead? See our API & SMTP bulk email gateway.
Built for deliverability & inbox placement
Getting to the inbox is engineering, not luck. We authenticate every message and protect sender reputation so your OTPs and receipts arrive on time.
SPF, DKIM & DMARC
We help you set up full email authentication with TLS in transit, so mailbox providers trust and accept your mail.
Dedicated IP & reputation
Dedicated IPs for high volume senders with guided warmup, plus warmed shared pools — kept clean for consistent placement.
Bounce & complaint handling
Hard bounces, spam complaints and unknown addresses are auto-suppressed so you never re-send to bad recipients.
Real-time tracking, webhooks & events
Know exactly what happens after you hit send. Every message emits events you can view in the dashboard or push to your systems in real time.
- Delivered, open & click — confirm the message reached the inbox and was engaged with.
- Bounce & spam events — catch hard/soft bounces and complaint feedback loops instantly.
- Webhooks — POST every event to your endpoint to sync CRM, trigger retries or alert on failures.
- Searchable logs — look up any message by ID, recipient or status with exportable history.
Email templates & dynamic content
Store your OTP, receipt and welcome designs once, then send them with per-recipient variables. Keep design out of your code and update copy without a redeploy.
Reusable templates
Version-controlled HTML templates referenced by ID from the API or relay.
Dynamic variables
Inject names, order numbers, OTPs and amounts with simple placeholders.
Unicode & localization
Send in regional and global languages with full Unicode support.
Transactional vs marketing email
Separating the two protects your sending reputation and keeps critical mail out of the promotions tab.
| Dimension | Transactional Email | Marketing Email |
|---|---|---|
| Trigger | User action or system event | Campaign scheduled by sender |
| Audience | Individual user, one-to-one | Segmented lists, one-to-many |
| Content | OTPs, receipts, alerts, resets | Offers, newsletters, promotions |
| Consent / opt-in | Implicit (relationship exists) | Explicit opt-in required |
| Unsubscribe link | Not required | Mandatory |
| Priority | High — time-sensitive | Standard — batchable |
| Typical IP | Dedicated, high-reputation | Separate marketing pool |
| Example | “Your OTP is 4821” | “Flat 40% off this weekend” |
Running campaigns too? Explore our promotional email API — and keep the two streams on separate reputations.
Transactional email use cases
OTP & 2FA
One-time passcodes and login verification delivered in seconds.
Password reset
Secure reset links that reach the inbox before the token expires.
Order & payment confirmations
Confirm purchases and payments the moment they complete.
Receipts & invoices
Deliver itemized receipts and invoices with dynamic totals.
Onboarding & welcome
Greet new users and verify their address the moment they sign up.
Notifications & alerts
Account, security and status alerts triggered by real-time events.
A transactional email partner built for the inbox
Trusted by 5,000+ businesses across India and 190+ countries, with 15+ years in messaging — the authentication, reputation and support that keep critical email delivered.
High inbox delivery
Full SPF/DKIM/DMARC authentication and clean IPs for consistent inbox placement.
99.9% uptime
Resilient infrastructure so OTPs and receipts send in seconds, around the clock.
API & SMTP ready
Integrate in minutes over REST or SMTP with docs, message IDs and webhooks.
24×7 human support
India-based team available any time to help with setup, DNS and deliverability.
One platform for every channel: SMS, Voice, WhatsApp & Email
Reach customers wherever they are from a single account and one set of credentials — add channels as you grow, with unified reporting across all of them.
SMS
Transactional and promotional SMS over DLT-compliant routes.
Voice
Voice OTPs, IVR and automated call alerts to any number.
Rich, verified WhatsApp Business messaging and notifications.
Transactional and marketing email over API and SMTP.
Explore transactional SMS and WhatsApp Business API.
Transparent, volume-based pricing
Pay for what you send, with per-email rates that drop as your volume grows. Dedicated IPs and priority support available for high-volume senders.
