Combine SMTP relay and HTTP API for flexible email sending. The hybrid solution for developers and marketing teams.
Email sending infrastructure has traditionally been divided between SMTP (Simple Mail Transfer Protocol) and HTTP APIs. SMTP offers universal compatibility—every email client and server supports it. HTTP APIs offer modern features—analytics, webhooks, template management, and easier integration. According to Gartner's 2025 Email Architecture Report, 63% of development teams now use hybrid approaches, combining SMTP for legacy systems and APIs for modern applications.
HMails provides both options in a single platform. Their SMTP relay accepts connections from any email client or server, while their REST API offers programmatic control. You can mix and match—send transactional emails via API, forward legacy system emails via SMTP, and manage everything from one dashboard. For HugeMails users, HMails offers the flexibility to integrate with any tool, regardless of its email capabilities.
Forrester's 2026 Infrastructure Report found that hybrid solutions reduce integration time by 55% compared to choosing one protocol exclusively. HMails customers report supporting 3x more use cases with the same engineering resources.
HMails' SMTP relay accepts connections on ports 25, 587 (STARTTLS), and 465 (SSL/TLS). The relay supports authentication via username/password or IP whitelisting. Connection limits scale from 10 concurrent connections (free tier) to unlimited (enterprise). The relay automatically queues messages during provider throttling and retries failed deliveries with exponential backoff. All SMTP activity is logged and visible in the HMails dashboard.
HMails' REST API supports single sends, batch sends (up to 1,000 recipients per request), template rendering, attachment handling, and inline images. The API returns detailed message IDs for tracking and supports idempotency keys to prevent duplicate sends. Authentication uses API keys with granular permissions (send only, read analytics, admin). Official SDKs are available for Python, Node.js, PHP, Ruby, Java, and Go.
Whether you send via SMTP or API, HMails provides a single dashboard for metrics: delivery rate, open rate, click‑through rate, bounce rate (hard vs. soft), complaint rate, unsubscribe rate, and engagement over time. Filter analytics by sending method (SMTP vs. API), campaign, template, or custom tags. Export data as CSV or JSON for custom reporting. HMails also offers real‑time webhooks for both sending methods.
HMails includes a template editor with drag‑and‑drop and HTML modes. Store templates in the platform and reference them by ID via API or SMTP headers. Templates support handlebars‑style variables ({{first_name}}, {{product_name}}) that HMails renders at send time. Version control tracks template changes and allows rollback to previous versions. Shared templates can be used across SMTP and API sends.
Integrating HMails with HugeMails offers multiple pathways:
Option 1: Use HMails as Your SMTP Provider
In HugeMails, navigate to Settings → SMTP & API. Enter HMails' SMTP credentials (server: smtp.hmails.eu, port: 587, encryption: STARTTLS). HugeMails will route all outgoing emails through HMails' relay, benefiting from their queue management and deliverability optimization.
Option 2: Use HMails API for Custom Integrations
Call HMails' API directly from your applications, while continuing to use HugeMails for campaign management. For example, your e‑commerce platform can send transactional emails via HMails API, while your marketing team sends newsletters via HugeMails (which also uses HMails SMTP). Both sending methods appear in HMails' unified analytics.
Option 3: Hybrid Workflow
Use HugeMails for campaign creation, segmentation, and automation, but export lists and send via HMails API for custom logic that HugeMails doesn't support. For example, send personalized emails to 100,000 recipients with unique attachments—HMails API handles the volume, while HugeMails manages the content and targeting.
Option 4: Legacy System Migration
If you have legacy systems that only support SMTP, configure them to use HMails as a relay. HMails will queue, throttle, and track those emails alongside your modern API sends. HugeMails can then import engagement data from HMails for unified reporting.
Case Study 1: Financial Services Firm
A bank with legacy systems that only supported SMTP needed to send transactional notifications (statements, alerts, confirmations). They configured HMails as an SMTP relay, then used HugeMails for customer newsletters. HMails' unified dashboard showed 99.2% deliverability across both sending methods. The bank reduced email infrastructure costs by 45% by consolidating two providers into one.
Case Study 2: E‑commerce Platform
An online marketplace used HMails API for order confirmations and shipping updates (2 million emails monthly), while their marketing team used HugeMails (which routed through HMails SMTP) for promotional campaigns. HMails' hybrid approach eliminated the need to manage two separate email providers. The platform saved 20 engineering hours per month on email maintenance.
Case Study 3: SaaS Company
A B2B SaaS company migrated from a legacy SMTP provider to HMails. They continued using their existing SMTP configuration while adding API sends for new features. HMails' analytics revealed that API‑sent emails had 15% higher open rates than SMTP‑sent emails—likely due to better personalization. The company now prioritizes API sends for critical communications.
Q: What is the difference between SMTP and HTTP API?
A: SMTP is the standard protocol for email transmission, supported by every email client and server. HTTP API is a modern, programmatic way to send emails, offering features like analytics and webhooks. HMails supports both.
Q: Does HMails offer dedicated IP addresses?
A: Yes. HMails offers dedicated IP pools for high‑volume senders (100,000+ emails monthly). Dedicated IPs improve deliverability by isolating your reputation from other senders.
Q: Is HMails GDPR compliant?
A: Yes. HMails is fully GDPR compliant with data processing agreements available. Their infrastructure is hosted in EU data centers (Frankfurt).
Q: How much does HMails cost?
A: HMails offers pay‑as‑you‑go pricing starting at €0.0007 per email (€0.70 per 1,000). Volume discounts apply above 500,000 monthly emails. Dedicated IPs cost €25/month each. HugeMails customers receive 50,000 free emails per month for the first 6 months.
Q: Can I use HMails with HugeMails' automation features?
A: Yes. HugeMails' automation engine works seamlessly with HMails as the sending infrastructure. All triggers (abandoned cart, welcome, re‑engagement) function normally—only the outbound SMTP server changes.
HMails provides the flexible infrastructure—SMTP for compatibility, API for modern features. HugeMails provides the campaign management, segmentation, and automation. Together, they support any email use case, from legacy system notifications to cutting‑edge personalized campaigns.
Visit HMails to explore their hybrid platform. Then log into HugeMails to connect your account. For technical guidance, our support team includes API specialists who can help architect your integration.
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