Enterprise-Grade Infrastructure

Email API

Enterprise-grade email infrastructure with cryptographic authenticity proofs, multi-provider failover, and real-time deliverability intelligence.

99.2%

Delivery Rate

4+

Providers

<800ms

Avg Latency

99.95%

Uptime SLA

Architecture

How We Built It

01

One API. Every Provider. Zero Downtime.

Email delivery is a reliability problem. SendGrid goes down — your transactional emails stall. Mailgun throttles — your campaigns miss deadlines. SMSLY Email abstracts four providers behind a single REST API. Adaptive routing selects the optimal provider based on real-time latency, deliverability scores, and cost. When a provider degrades, failover is automatic — no retry logic needed on your side. Same API key, same payload format, same webhooks. Your code never changes.

02

Cryptographic Authenticity. Not Just Headers.

Every outbound email is stamped with a cryptographic hash-chain proof — not just DKIM signatures, but a verifiable chain of authenticity that links back to your verified sender identity. Recipients verify with one click. Unstamped emails from stamped senders trigger fraud warnings. This is the difference between "probably real" and "cryptographically proven." BEC attacks, CEO fraud, and domain spoofing become mathematically impossible against your brand.

03

Deliverability Is a Science, Not a Guess.

Inbox placement varies by ISP, time of day, content, and sender reputation. SMSLY tracks delivery outcomes across 50+ ISPs in real time. Spam score testing runs before every campaign. IP warmup scheduling gradually increases volume to build reputation. Deliverability dashboards show per-ISP performance. When a mailbox provider changes its filtering rules, you know within hours — not weeks.

04

Multi-Tenant by Design, Not by Accident.

SaaS platforms need email isolation — Tenant A's reputation cannot affect Tenant B's deliverability. SMSLY Email assigns dedicated API keys, IP pools, and reputation scores per tenant. Rate limits are enforced per-tenant. Suppression lists are isolated. Webhook delivery is per-tenant. One platform, thousands of isolated email environments. Your customers never see each other's data, reputation, or throughput.

05

Inbound Is the Other Half of Email.

Most email platforms only handle outbound. SMSLY parses inbound email via IMAP, extracts RFC822 content, and routes to your webhooks. Attachments are decoded and stored. Routing rules match on sender, subject, headers, or content. Build automated response systems, ticket creation flows, and compliance pipelines — all triggered by incoming email without polling.

Capabilities

Built for Production

Every feature designed for reliability at scale. No compromises.

Multi-Provider Failover

Automatic failover across SMTP, SendGrid, Mailgun, and SES. If one provider degrades, the next takes over in under 200ms — delivery never stops.

MIP Stamping

Every outbound email gets a cryptographic hash-chain proof. Recipients verify authenticity with one click. Stops BEC, CEO fraud, and spoofing at the protocol level.

DKIM + SPF + DMARC

Full authentication suite with automatic key rotation. Guided DNS setup wizard gets your domain verified in under 5 minutes.

Deliverability Intelligence

Real-time inbox placement tracking across Gmail, Outlook, Yahoo, and 50+ ISPs. Spam score testing before every campaign. IP warmup scheduling built in.

Template Engine

Handlebars-powered templates with dynamic variables, conditional blocks, and HTML/text dual rendering. Lock templates to prevent unauthorized modifications.

Real-Time Webhooks

Delivery, open, click, bounce, and complaint events pushed to your endpoint instantly. HMAC-signed payloads. Exponential backoff retries with dead-letter replay.

Inbound Parsing

IMAP integration with automatic RFC822 parsing. Route inbound emails to webhooks, extract attachments, and trigger automated response flows.

Suppression Management

Automatic hard bounce and complaint suppression. Import/export lists. Global suppression database prevents re-sending to problematic addresses.

Multi-Tenant Isolation

Per-tenant API keys, rate limits, and deliverability isolation. Each tenant gets dedicated IP pools and reputation tracking. One platform, zero cross-tenant contamination.

A/B Testing

Split test subject lines, content, and send times. Auto-select winning variants based on open/click rates. Statistical significance calculations built in.

Integration

Start in Minutes

Drop-in SDKs for every major language. One API call to get started.

Applications

Enterprise Use Cases

Transactional Email

Password resets, order confirmations, shipping notifications, and receipt delivery with guaranteed inbox placement and sub-second latency.

Marketing Campaigns

Newsletters, product announcements, and promotional campaigns with dynamic content blocks, A/B testing, and send-time optimization.

Anti-BEC Protection

MIP-stamped emails let recipients verify that executive communications are authentic. Prevents CEO fraud, wire transfer scams, and domain spoofing.

SaaS Notifications

Multi-tenant notification systems with per-tenant templates, rate limiting, and deliverability isolation. One API, thousands of tenants.

Compliance & Audit Trails

Cryptographic email proofs for SOC 2, HIPAA, and GDPR audits. Every email gets a tamper-evident record with timestamp and delivery proof.

Inbound Email Automation

Parse inbound emails, extract attachments, route to webhooks, and trigger automated response flows. Build email-driven workflows without polling.

Healthcare Communications

HIPAA-compliant email delivery with encryption at rest and in transit. Patient notifications, appointment reminders, and lab results with delivery proof.

Financial Services

PCI-compliant email for statements, fraud alerts, and wire confirmations. Cryptographic proofs satisfy audit requirements for financial communications.

Onboarding

How It Works

1

Configure Your Domain

Add your sending domain and configure SPF, DKIM, and DMARC records through our guided setup wizard. Domain verification completes in under 5 minutes.

2

Send via API or SMTP

Use the REST API for full control — attachments, templates, scheduling, webhooks. Or use SMTP relay for drop-in compatibility with existing systems. Same deliverability either way.

3

Enable MIP Stamping

Toggle cryptographic email stamping in your project settings. Every outbound email automatically gets a hash-chain proof. Recipients verify with one click.

4

Set Up Webhooks

Register your HTTPS endpoint for real-time delivery events. HMAC-signed payloads verify authenticity. Exponential backoff retries ensure delivery.

5

Configure Inbound Parsing

Point your MX records to SMSLY. Inbound emails are automatically parsed, attachments extracted, and routed to your webhooks in real-time.

6

Monitor & Optimize

Track deliverability, engagement, and reputation across ISPs in real time. Spam test before campaigns. IP warmup scheduling builds reputation automatically.

Enterprise-Grade Security & Reliability

SOC 2 Compliant

Audited annually

Encryption at Rest

AES-256

99.95% Uptime SLA

Guaranteed

Multi-Region

3 regions active

Ready to Ship with Confidence?

Start with our free tier — no credit card required. Scale to millions of messages with enterprise support, custom SLAs, and dedicated infrastructure.

Free tier includes 1,000 emails/month. No credit card required. Enterprise plans include dedicated IPs, custom SLAs, and 24/7 support.