Uma API prática para equipes que entregam rápido
Envie OTPs, redefinições de senha, alertas de conta, faturas e mensagens de ciclo de vida a partir de uma única API. A Sendarix foi desenhada para comportamento previsível em escala, não integrações frágeis.
Autentique solicitações, envie mensagens e acompanhe resultados em um pipeline consistente. Cada envio pode ser observado por meio de logs, eventos e webhooks.
API calls flow through structured validation, queue management, and email routing before reaching destination servers. Delivery outcomes are surfaced via email webhooks and tracked in email analytics.
O que você obtém
A API é intencionalmente direta: criar e enviar mensagens, inspecionar resultados e automatizar reações. Isso ajuda equipes de produto a avançar mais rápido sem abrir mão da confiabilidade.
Integração REST rápida
Padrões claros de requisição/resposta e comportamento previsível para serviços de backend modernos e ferramentas internas.
Rastreamento do ciclo de vida da mensagem
Acompanhe estados aceitos, entregues, com falha (bounce) e reclamações para que o produto reaja em tempo real.
Visibilidade operacional
Logs pesquisáveis e fluxos de eventos reduzem o tempo de solução quando usuários relatam problemas de entrega.
Escale sem reescrever tudo
De cargas iniciais a fluxos de alto volume, mantenha um único contrato de API conforme o volume cresce.
Injeção de dados em modelos
Passe variáveis dinâmicas de forma organizada para que modelos transacionais permaneçam consistentes entre produtos.
Padrões de envio idempotentes
Evite envios duplicados em cenários de nova tentativa com estratégias determinísticas de tratamento de requisições.
What Happens After an API Send Request
A successful API response is the start of the message lifecycle, not the end of it.
Validation
The system checks authentication, request shape, sender identity, and required fields before accepting the request.
Acceptance and Queueing
A successful response means the request has been accepted for processing. It does not necessarily mean the message has already been delivered to the destination server.
Delivery Processing
After acceptance, the message moves through delivery logic that may include queueing, suppression checks, routing policy, and destination-aware pacing.
Event Generation
As the message progresses, delivery events can be exposed to logs, analytics, and webhook consumers so your application can react in near real time. Monitor progression via email analytics or email webhooks.
Why Accepted Does Not Mean Delivered
A successful API response confirms that the request has been accepted into the processing pipeline. Final delivery still depends on validation, suppression checks, routing policy, provider behavior, and downstream delivery outcomes.
Email API vs SMTP Relay
Both approaches can send email, but they solve different integration needs.
Email API
Best for modern applications that want structured requests, cleaner metadata, and easier automation around delivery state. See API docs for integration details.
SMTP Relay
Best for older tools, legacy systems, or environments that already speak SMTP and need compatibility with minimal code changes. See SMTP relay for setup details.
Many teams use an email API for product-driven workflows and SMTP relay for compatibility with older tools, internal systems, or third-party applications that already speak SMTP. Check API docs for implementation, email webhooks for event handling, and email analytics for delivery visibility.
Fluxo típico da API
Um padrão simples que sua equipe pode implementar uma vez e reutilizar em todos os cenários transacionais.
1. Enviar solicitação
Seu serviço envia o payload com destinatário, dados do modelo e metadados.
2. Validar e enfileirar
Verificações de entrada, lógica de supressão e enfileiramento ocorrem antes da etapa de entrega.
3. Entregar
As mensagens são roteadas para provedores de destino com comportamento de envio controlado.
4. Consumir eventos
Use webhooks e logs para atualizar o estado do produto e acionar automações downstream.
Real-World Scenario: Idempotent Send Request
A payment confirmation is triggered by a webhook from a payment processor. The application sends via the email API with an idempotency key. If the API call is accidentally retried due to a network timeout, the email routing layer recognizes the duplicate and returns the original queued message ID rather than queuing a second send. Delivery is confirmed via email webhooks.
Example API Request Flow
- Client sends request to API docs
- Request is validated
- Message is queued
- Delivery attempt is executed
- Events are generated and tracked via email webhooks
Note: A successful API response (e.g. 202 Accepted) means the message is queued, not delivered. Track final delivery status with email analytics or webhook events.
Example API Request and Response
Every Sendarix API call uses JSON and returns consistent response shapes. Below are the primary endpoints your integration will call most frequently.
Send Message
POST to /v1/messages with recipient, subject, and template data. Returns a message_id for correlation with downstream webhook events.
POST /v1/messages
Authorization: Bearer sk_live_...
Content-Type: application/json
{
"recipient": "user@example.com",
"subject": "Your verification code",
"template": "otp-code",
"template_data": {
"code": "847291",
"expires_in": "5 minutes"
},
"headers": {
"X-Idempotency-Key": "uuid-v4-here"
}
}
{
"message_id": "msg_abc123xyz",
"status": "queued",
"recipient": "user@example.com",
"created_at": "2026-04-19T14:30:00Z"
}
Returns a message_id and status: queued. Correlate message_id with email webhooks for delivery status.
List Messages
GET /v1/messages returns a paginated list of messages with filtering by status, recipient, and date range.
GET /v1/messages?status=delivered&limit=25 Authorization: Bearer sk_live_...
Get Message
GET /v1/messages/{message_id} returns the current state of a specific message including timestamps, recipient, and delivery outcome.
GET /v1/messages/msg_abc123xyz Authorization: Bearer sk_live_...
Cancel Scheduled Message
DELETE /v1/messages/{message_id} cancels a scheduled message before it is delivered. Returns 404 if already sent.
DELETE /v1/messages/msg_abc123xyz Authorization: Bearer sk_live_...
Add to Suppression List
POST /v1/suppressions adds an address to the suppression list to prevent future sends to that recipient.
POST /v1/suppressions
Authorization: Bearer sk_live_...
{
"recipient": "user@example.com",
"reason": "user_unsubscribed"
}
Validation, Queueing, and Delivery Lifecycle
Understanding what happens between an API call and final delivery helps you design more resilient integrations and debug issues faster.
Step 1: Request Validation
The API validates: required fields (recipient, from, subject), email address format, API key and permissions, content size limits. Validation errors return 400 or 422 immediately with a field-level error array. No message is queued until validation passes.
Step 2: Queue and Acceptance
Validated messages enter the sending queue with a queued status. A message_id is returned immediately so your application can correlate with downstream events. Queue processing is FIFO within priority tiers.
Step 3: Routing and Provider Selection
The routing layer selects the optimal sending path based on recipient domain, IP reputation, and provider performance. This is handled automatically by Sendarix infrastructure.
Step 4: Delivery Attempt
The message is delivered to the recipient's mail server. Delivery outcomes (delivered, bounced, deferred) are posted to your configured webhook endpoint. Track delivery in the email analytics dashboard.
Event Timeline
Each message generates a timeline of events: queued → accepted → delivered/bounced/deferred. You receive webhook events for each state change. Between queued and final state, multiple deferred events may fire as the system retries temporary failures.
Retry Behavior for Deferred Messages
Deferred messages (temporary provider rejection, greylisting) are retried automatically at increasing intervals: 30 seconds, 5 minutes, 30 minutes, 2 hours, 5 hours. After 6 attempts, the message is marked as permanently bounced and you receive a bounce event.
Error Handling and Retry-Safe Integration Patterns
A production-grade integration handles API errors gracefully. These patterns prevent duplicate sends, data inconsistency, and user-facing failures.
HTTP Status Code Reference
Map status codes to retry behavior:
200
— Success — no retry needed
400
— Bad request — fix payload before retrying
401
— Unauthorized — check API key, do not retry
422
— Validation failed — fix payload, do not retry
429
— Rate limited — retry after X-RateLimit-Reset
500
— Server error — retry with exponential backoff
503
— Service unavailable — retry with backoff
Idempotent Send Pattern
Pass an idempotency_key (UUID v4 recommended) in the request headers: Idempotency-Key: {uuid}. If the same idempotency_key is submitted twice within 24 hours, the API returns the original response without re-sending. This prevents duplicate sends during retry loops.
Correlating API Calls to Events
Every message response includes a message_id. Match this against the message_id in email webhooks to confirm delivery. Never assume a 200 OK means the email was delivered — a 200 confirms the message was queued.
Exponential Backoff Implementation
Use this backoff formula: delay = min(base * 2^attempt + jitter, max_delay). Recommended base: 1 second, max_delay: 60 seconds, jitter: 0-1000ms random. Always cap retries at a maximum of 5 attempts to avoid infinite loops.
Dead-Letter Handling
After exhausting retries, log permanently failed messages to a dead-letter table keyed on message_id. Inspect these periodically to identify systemic issues (bad address patterns, provider problems, template errors) and fix upstream.
Common Email API Use Cases
The Sendarix API handles all transactional email flows. These are the most common integration patterns.
One-Time Passwords (OTP)
Send time-sensitive OTP codes for login, password changes, and identity verification. OTP emails require low latency, high deliverability, and clean templates with no distracting content. Set a short TTL in your application — OTP codes are security-sensitive and should not persist in inboxes.
Password Reset Emails
Password reset links must reach users quickly and reliably. These are high-stakes flows — a missed reset email creates support tickets and churn. Pair with email webhooks to detect bounce events and alert security teams if reset emails are bouncing for active users.
Billing and Invoice Notifications
Invoice delivery, payment confirmations, and failed payment alerts drive user engagement with billing systems. Use template data injection to personalize invoice amounts and due dates. For failed payments, trigger retry logic in your system based on the bounce event.
Account Lifecycle Notifications
Welcome emails, email verification, account suspension, and deletion notices are all driven by user actions in your system. These flows work best with an idempotency key per user action to prevent duplicate sends when users trigger the same action multiple times.
System and Security Alerts
New login detected, password changed, device authorized, unusual activity alerts — these require immediate delivery to catch security incidents. Route these through your highest-priority sending path. Set up real-time email analytics alerts for spike patterns that may indicate a compromised account.
Integrate with Your Email Infrastructure
The Email API works alongside SMTP relay for legacy system migration, transactional email templates for content management, and email analytics for cross-channel performance reporting. Build a complete email stack with the API at the center.
Combina bem com
A API de e-mail funciona especialmente bem com Webhooks de e-mail para automação em tempo real e Análise de e-mail para insight operacional.
Quem usa
Produtos SaaS, equipes de plataforma, sistemas de conta, motores de faturamento e fluxos de suporte que dependem de entrega de e-mail consistente.
Need SMTP configuration for a specific provider? Check our step-by-step guides for Gmail SMTP settings, Outlook SMTP configuration, Office 365 setup, Yahoo SMTP settings, and SendGrid SMTP settings.
What sets Sendarix apart: The Sendarix email API is designed around infrastructure control — routing rules, queue behavior, and delivery policy are exposed through the API, giving engineering teams programmatic access to what most platforms hide behind dashboards.
Perguntas frequentes
Podemos usar API e SMTP juntos?
Sim. Muitas equipes usam a API para fluxos de aplicação e SMTP para sistemas legados durante a migração.
Recebemos dados de evento para cada mensagem?
Sim. Eventos de entrega, falha (bounce) e reclamação estão disponíveis para fluxos operacionais e de produto.
É adequado para tráfego de alto volume?
Sim. O mesmo modelo de API é usado desde fases de baixo volume até envio sustentado em alto volume.
Precisamos de SPF, DKIM e DMARC para envio via API?
Autenticar o domínio de envio é altamente recomendado. Melhora como os provedores de caixa de entrada avaliam seu e-mail e é uma expectativa básica para tráfego em produção.
Como funcionam chaves de API e permissões?
Você pode emitir chaves para diferentes ambientes ou serviços e restringir o que cada chave pode fazer, mantendo staging, CI e produção isolados.
O que acontece se nossa integração enviar solicitações inválidas ou duplicadas?
A API retorna erros de validação claros para payloads incorretos. Para novas tentativas, use identificadores estáveis na camada de aplicativo para não enviar duas vezes o mesmo e-mail voltado ao usuário.
Podemos correlacionar chamadas de API com a entrega downstream?
Sim. Identificadores de mensagem e linhas do tempo de eventos permitem ligar um envio específico da API a resultados aceitos, entregues, com falha ou adiados.
A API de e-mail é adequada para redefinições de senha e códigos OTP?
Sim. Esses fluxos são casos transacionais clássicos: expectativa de baixa latência, alta necessidade de visibilidade e acoplamento forte aos sistemas de autenticação ou risco.
Devemos usar apenas HTTPS para o tráfego da API?
Sim. TLS protege credenciais e metadados de mensagens em trânsito. Trate os endpoints da API como qualquer outra superfície de produção que carrega segredos.
What is the request rate limit on the Email API?
Rate limits vary by plan. Standard plans allow 1,000 requests/minute; enterprise plans support higher throughput. Rate limit headers are included in every response (X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset). Exceeding the limit returns 429 Too Many Requests.
How do we handle API failures gracefully in our application?
Implement exponential backoff with jitter for retries. Treat 429 as a signal to slow down, 5xx as transient errors to retry, and 4xx (except 429) as permanent failures that should not retry. Store the message_id from successful submissions to correlate with downstream webhook events.
What is the maximum message size via API?
Messages up to 50MB total payload are accepted. For files larger than 25MB, Sendarix recommends hosting files externally and including a signed download link in the email body rather than attaching directly. Some mail servers reject messages exceeding 25MB.
Can we schedule email delivery for a future time?
Yes. Pass a scheduled_time parameter (ISO 8601 UTC timestamp) in your API request. Messages are queued and delivered at the specified time. Scheduled messages can be cancelled before delivery by calling the message cancel endpoint with the message_id.
How do we handle unsubscribe programmatically via the API?
The API provides /unsubscribes endpoints for managing suppression records. When a user unsubscribes, add them via the API to prevent future sends to that address. This integrates with the email webhooks unsubscribe event for automatic suppression list updates.
What response codes should our retry logic handle?
Handle these specifically: 200 OK (success, no retry), 400 Bad Request (invalid payload, fix before retry), 401 Unauthorized (invalid API key, do not retry), 422 Unprocessable Entity (validation error, fix payload), 429 Too Many Requests (rate limited, retry after X-RateLimit-Reset), 500 Internal Server Error (transient, retry with backoff).
Pronto para migrar para uma infraestrutura de e-mail confiável?
Comece grátis sem cartão ou fale com vendas para alto volume e enterprise.
Começar a enviarFalar com vendas