An Email API built for the inbox, not just the send
CommLeap's Email API and SMTP relay deliver transactional and bulk email with authentication, reputation management and real-time events built in. It is a transactional email service that sits alongside WhatsApp, SMS and Voice on one platform, so email becomes part of every customer journey rather than a separate system.
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Everything a modern email delivery platform should do
Password resets, receipts, statements, alerts and newsletters each place different demands on your email stack. CommLeap handles them through one service, with the controls to keep critical mail separate from promotional volume.
REST API and SMTP relay
Send over HTTPS with JSON, or point existing applications at the SMTP relay with TLS. Both paths share the same logs, suppression lists and events.
Domain authentication
Guided DNS setup for SPF, DKIM and DMARC, with record validation, key rotation and alignment checks for every sending domain and subdomain.
Shared and dedicated IPs
Start on managed shared pools or isolate your reputation on dedicated IPs, with warm-up schedules and separate pools for transactional and marketing mail.
Templates and localization
Versioned templates with dynamic variables, conditional blocks and locale variants, so one template can serve every market and language you support.
Suppression and bounce handling
Hard bounces, complaints and unsubscribes are suppressed automatically, while soft bounces are retried based on the receiving server's response.
Engagement analytics
Delivery, bounce, open and click tracking by domain, template, campaign and mailbox provider, with raw events available through webhooks.
Inbound email parsing
Receive replies and incoming mail on a subdomain and get each message as structured JSON, attachments included, posted to your webhook.
Multichannel fallback Coming soon
You will be able to use email as an automatic fallback for WhatsApp or SMS with a single parameter. Today, you can add email as a step in automated journeys.
Team and account controls
Subaccounts per brand or region, scoped API keys and role-based access keep sending governed as your organization grows. Audit logs are coming soon.
From domain setup to your first monitored send
Most deliverability problems start with configuration. We guide you through the setup in the order mailbox providers care about.
Authenticate your domain
Add the SPF, DKIM and DMARC records CommLeap generates for you. The console checks each record and flags alignment issues before you send.
Build your templates
Create templates in the editor or upload your own HTML, define variables and locale variants, then preview with sample data across common clients.
Send through the API
Call POST /v1/messages with channel "email", or connect your SMTP client. Idempotency keys prevent duplicates when your systems retry.
Monitor and improve
Watch delivery, bounces and complaints by mailbox provider, subscribe to webhook events, and adjust volume or content when trends change.
Shared or dedicated IPs: choose the right model for your volume
Mailbox providers judge your mail on both domain and IP reputation. The right IP model depends on how much you send and how consistently. For high-volume bulk email, a dedicated IP gives you control, but only after it has been warmed up gradually.
- Warm-up plans that raise daily volume step by step, starting with your most engaged recipients
- Separate IP pools and subdomains for transactional and marketing streams
- Reverse DNS configured for dedicated IPs and TLS wherever the receiving server supports it
- Provider-level throttling that respects deferrals instead of pushing through them
| Consideration | Shared IP pool | Dedicated IP |
|---|---|---|
| Best for | Low, variable or seasonal volume | Consistent high volume |
| Reputation | Shared with other vetted senders and managed by CommLeap | Determined by your own sending behavior |
| Warm-up | Not required | Required, with a gradual ramp by provider |
| Control | Managed for you | Full control, including stream separation |
Meeting the Gmail and Yahoo bulk-sender requirements
Since February 2024, Gmail and Yahoo have required bulk senders to authenticate their mail, make unsubscribing easy and keep complaints low. Google defines bulk senders as those sending 5,000 or more messages a day to personal Gmail accounts, and once classified, that status is permanent. Since May 2025, Microsoft has applied similar authentication requirements to domains sending more than 5,000 messages a day to Outlook.com addresses. CommLeap is designed to help you meet each requirement.
Authenticate every message
Bulk senders need SPF, DKIM and a DMARC policy, with the visible From domain aligned to SPF or DKIM. CommLeap generates the records, validates them and alerts you if alignment breaks.
Offer one-click unsubscribe
Marketing and subscribed messages must support one-click unsubscribe as defined in RFC 8058. CommLeap adds the List-Unsubscribe headers and processes requests automatically, helping you honor them within the two days (48 hours) that Google recommends and Yahoo requires.
Keep spam complaints low
Google recommends keeping user-reported spam rates below 0.1% and never reaching 0.3%, and Yahoo also sets a 0.3% ceiling. Complaint feedback is suppressed automatically, and trends by stream and template help you spot problems early.
Mailbox provider requirements change over time, and since November 2025 Gmail has been ramping up enforcement, including temporary and permanent rejections of non-compliant messages. Refer to Google's email sender guidelines, Yahoo's sender best practices and Microsoft's Outlook.com sender requirements for the current rules. Compliance with these rules remains the sender's responsibility.
Send a transactional email with one request
Email uses the same endpoint, authentication and event model as every other CommLeap channel. Reference a template, pass your variables, and receive delivery, bounce and engagement events on your webhook.
- Events for sent, delivered, bounced, complained, opened and clicked
- Custom metadata and tags returned on every event for easy reconciliation
- Idempotent sends for safe retries; signed webhooks Coming soon
Email delivery best practices we help you put in place
Good deliverability is the result of many small decisions made consistently. These are the practices our team reviews with enterprise senders during onboarding.
Infrastructure
- SPF, DKIM and DMARC published and aligned for each sending domain
- A DMARC policy that progresses from monitoring toward enforcement
- Separate subdomains for transactional and marketing mail
- Reverse DNS and TLS in place for every sending IP
List quality
- Clear, recorded consent for marketing email
- No purchased or rented lists
- Automatic suppression of hard bounces and complaints
- Regular sunsetting of recipients who have stopped engaging
Content and headers
- A recognizable From name and a monitored reply address
- One-click unsubscribe on marketing and subscribed messages
- Balanced HTML with a plain-text part and descriptive link text
- Consistent branding so recipients recognize your messages
Monitoring
- Complaint rates kept below 0.1% and well away from Google's 0.3% limit
- Bounce and deferral trends watched by mailbox provider
- Google Postmaster Tools connected for your domains
- Volume increases planned rather than sudden
Email as part of a multichannel journey
Customers do not think in channels, and your messaging should not either. Because email runs on the same platform as WhatsApp, SMS and Voice, you can combine them without stitching together separate providers.
- Automatic fallback Coming soon to email when a WhatsApp or SMS message cannot be delivered
- Offer email as a channel for one-time passwords through the Verify API
- Follow a WhatsApp conversation with a detailed email receipt or document
- Build email steps into campaigns and journeys triggered by customer events
- Route inbound email replies into the omnichannel inbox alongside chat
Email API questions, answered
What is an email API?
An email API lets your applications send, track and receive email programmatically over HTTPS instead of running your own mail servers. CommLeap's Email API handles message assembly, templating, queuing, delivery to mailbox providers, bounce and complaint processing, and event webhooks, so your team can focus on the content and timing of each message.
Should we use the REST API or the SMTP relay?
Use the REST API for new integrations: it supports templates, variables, idempotency keys and per-message metadata in one request, and multichannel fallback is coming soon. Use the SMTP relay when an existing application, CMS or legacy system already speaks SMTP and you want to route its mail through CommLeap without code changes. Both paths share the same authentication, suppression lists and analytics.
How does CommLeap help us meet the Gmail and Yahoo bulk-sender requirements?
CommLeap guides you through SPF, DKIM and DMARC setup with domain alignment, adds RFC 8058 one-click unsubscribe headers to marketing and subscribed messages, processes unsubscribes automatically, and surfaces complaint and bounce trends so you can act early. Google recommends keeping user-reported spam rates below 0.1% and never reaching 0.3% or higher. Meeting the requirements remains your responsibility as the sender and also depends on your list practices and content, which our team can review with you.
Do we need a dedicated IP address?
Not always. Shared IP pools suit lower or irregular volumes, because a steady flow of mail from many well-behaved senders helps keep reputation stable. Dedicated IPs make sense for consistent high volume where you want full control over your sending reputation. If you move to a dedicated IP, CommLeap provides a warm-up plan that increases volume gradually by mailbox provider.
How are bounces and spam complaints handled?
Hard bounces and spam complaints are added to your suppression list automatically, so future sends to those addresses are blocked before they reach a mailbox provider. Soft bounces are retried according to the provider's response. Every bounce and complaint is also delivered to your systems as a webhook event, so you can update your CRM or prompt the customer for a new address.
Can we receive and process inbound email?
Yes. Point an MX record for a subdomain at CommLeap and incoming messages are parsed into structured JSON, including sender, recipients, subject, text and HTML bodies and attachments, then posted to your webhook as a message.inbound event. Common uses include reply handling, support ticket creation and document intake.
Can email work alongside WhatsApp and SMS?
Yes. Email uses the same API, webhooks and event model as CommLeap's other channels. You can send receipts by email after a WhatsApp conversation or include email as a channel in verification and campaign journeys. Automatic fallback to email when a WhatsApp or SMS message fails is coming soon.
How is email priced?
Email is priced by monthly volume, with options for dedicated IPs and additional features such as inbound parsing, with extended data-retention options coming soon. Ask for a quote based on your volumes.
Connect email to the rest of your stack
Verify API
One-time passwords over WhatsApp, SMS, voice and email; automatic fallback and fraud controls coming soon.
Learn moreCampaigns & Journeys
Segmented broadcasts and automated journeys across WhatsApp, SMS and email.
Learn moreDevelopers
One REST API and webhooks across CommLeap channels; sandbox coming soon.
Learn morePut your email on infrastructure built for deliverability
Tell us about your domains, volumes and current provider. We'll help you plan authentication, IP strategy and warm-up, and connect email to the rest of your customer journeys.
- Solution design with a named specialist
- WhatsApp onboarding and verification support
- Transparent, volume-based pricing