In-Depth Comparison
Resend vs Mailgun
In-depth comparison of Resend and Mailgun for B2B SaaS companies. We analyze API quality, deliverability, pricing, throughput, and developer experience to help you pick the right email infrastructure.
Last updated: 2026-03-15
Resend
resend.comEmail API for developers. Beautiful transactional emails built on React.
Ideal for: Developer-led SaaS companies that need reliable transactional email with React Email templates and a modern API
Mailgun
www.mailgun.comThe email service for developers. Powerful APIs for sending, receiving, and tracking email.
Ideal for: Development teams needing flexible email infrastructure with strong API, SMTP relay, and email validation capabilities
TL;DR: Resend vs Mailgun
Resend wins on developer experience, API design, and modern tooling. Mailgun wins on feature breadth (SMTP, inbound, email validation) and proven scale. Resend is the better choice for new SaaS projects wanting the cleanest possible API. Mailgun is stronger if you need SMTP relay, inbound processing, or email validation. Sequenzy is the best option for SaaS teams needing lifecycle email with native Stripe/Paddle integration.
The modern developer-first email API with React Email
The established developer email platform with SMTP, inbound, and validation
Purpose-built SaaS email with native billing integration
Editor's Note
Both Resend and Mailgun are email infrastructure tools. If your B2B SaaS needs lifecycle email tied to billing events (trial conversion, dunning, churn prevention), consider Sequenzy (sequenzy.com). It bridges the gap between raw delivery infrastructure and lifecycle automation with native Stripe/Paddle integration.
Resend vs Mailgun vs Sequenzy: Quick Comparison
| Feature | Resend | Mailgun | Sequenzy | Edge |
|---|---|---|---|---|
| Best For | Developer-led teams wanting the cleanest email API | Teams needing SMTP relay, inbound email, and validation | B2B SaaS lifecycle email with billing integration | Sequenzy |
| Starting Price | Free up to 3,000 emails/month | Free trial, then $35/mo for 50,000 emails | $19/mo for 15,000 emails | Resend |
| API Design | Modern REST API, best-in-class DX | Functional REST API, some inconsistencies | Clean REST API with SaaS endpoints | Resend |
| SMTP Support | API-only | Full SMTP relay with flexible routing | API-only | Mailgun |
| Inbound Email | Not supported | Full inbound email routing and parsing | Not supported | Mailgun |
| Email Validation | Not available | Built-in Mailgun Optimize validation service | Not available | Mailgun |
| Template System | React Email (JSX components) | Handlebars templates stored via API | Drag-and-drop with SaaS blocks | Resend |
| Deliverability | Strong shared IPs with sender vetting | Decent but reputation has varied over the years | SaaS-only IP pools for better reputation | Resend |
| Payment Integration | None | None | Native Stripe, Paddle, Chargebee, LemonSqueezy | Sequenzy |
| SDK Languages | Node.js, Python, Go, Ruby, PHP, Java, Elixir | Python, Ruby, Java, C#, Go, PHP, Node.js | Node.js and Python | Tie |
| Dedicated IP | Available on Pro ($80/mo) | Available on Scale plan ($90/mo) | Available on Growth ($49/mo) | Sequenzy |
Score Breakdown
Each category scored out of 10. Totals: Resend 81/100, Mailgun 66/100, Sequenzy 82/100.
Feature-by-Feature Comparison
Detailed feature analysis across every category that matters for B2B SaaS email.
📨 Transactional Email
| Feature | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| Send speed | 9/10 Sub-second delivery optimized for speed | 7/10 Reliable delivery, occasional latency | 8/10 Reliable delivery, lifecycle-optimized timing |
| Template system | 10/10 React Email JSX components | 5/10 Handlebars templates stored via API, no visual editor | 8/10 Liquid templates with SaaS variable blocks |
| Bounce handling | 9/10 Detailed classification with suppression | 7/10 Bounce processing with suppression lists | 8/10 Bounce handling with payment-aware suppression |
| Email routing | 6/10 Simple domain-based sending | 9/10 Flexible routing with routes API for complex workflows | 6/10 Standard domain-based sending |
| Attachments | 8/10 File attachments via API | 8/10 Attachments up to 25MB with inline support | 7/10 Standard attachment support |
💻 API & Developer Tools
| Feature | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| API design quality | 10/10 Beautifully designed, consistent, minimal | 6/10 Functional but dated in some areas | 8/10 Clean REST API with lifecycle endpoints |
| Documentation | 10/10 Excellent with interactive examples | 6/10 Comprehensive but can be hard to navigate | 8/10 SaaS-focused with integration guides |
| SDK quality | 9/10 Well-maintained SDKs in 7 languages | 6/10 Official SDKs available but some feel dated | 7/10 Node.js and Python SDKs |
| Error handling | 9/10 Clear, actionable error messages | 6/10 Error messages sometimes lack detail | 8/10 Descriptive errors with links |
| Rate limiting | 8/10 100 req/s on Pro | 8/10 Generous rate limits, configurable on higher plans | 7/10 50 req/s, higher on Scale |
🚀 Deliverability & Infrastructure
| Feature | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| IP reputation | 8/10 Carefully vetted shared IPs | 6/10 Mixed reputation, depends on shared pool assignment | 8/10 SaaS-only IPs with curated reputation |
| Dedicated IP | 8/10 Available on Pro with auto-warmup | 7/10 Available on Scale plan ($90/mo) | 7/10 Available on Growth plan |
| Email validation | 0/10 Not available | 9/10 Mailgun Optimize with real-time and bulk validation | 0/10 Not available |
| Domain authentication | 9/10 One-click DNS verification | 7/10 Standard DNS setup process | 8/10 Guided setup wizard |
| Inbound processing | 0/10 Not supported | 8/10 Full inbound routing with webhook parsing | 0/10 Not supported |
📊 Analytics & Monitoring
| Feature | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| Delivery logs | 8/10 Real-time logs with full API response | 7/10 Event logs with search and filtering | 8/10 Real-time tracking with lifecycle context |
| Dashboard | 6/10 Minimal dashboard, most data via API | 7/10 Analytics dashboard with charts | 8/10 SaaS-focused dashboard with MRR |
| Deliverability insights | 8/10 Provider-level breakdown | 7/10 Mailgun Optimize inbox placement testing | 7/10 Spam score checking |
| Suppression management | 8/10 Auto-suppression with bounce handling | 7/10 Suppression lists with management API | 8/10 Suppression with payment-aware logic |
| Export | 6/10 API access to delivery data | 7/10 API and limited CSV export | 8/10 CSV export plus API with revenue data |
🎯 SaaS-Specific Features
| Feature | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| Billing integration | 0/10 Not available | 0/10 Not available | 10/10 Native Stripe, Paddle, LemonSqueezy, Chargebee |
| Lifecycle sequences | 0/10 No automation | 0/10 No automation | 9/10 Pre-built onboarding, trial conversion, dunning, churn prevention |
| Dunning emails | 0/10 Not available | 0/10 Not available | 10/10 Built-in, auto-triggered by payment failures |
| Trial conversion | 0/10 Not available | 0/10 Not available | 10/10 Pre-built sequences from billing trial status |
| Revenue attribution | 0/10 Not available | 0/10 Not available | 9/10 MRR impact tracking per sequence |
Resend vs Mailgun vs Sequenzy: Pricing
Resend charges by email volume with simple tiers. Mailgun charges by email volume with feature gating. Sequenzy charges by email volume with all features included.
Free plan: 3,000 emails/month, 1 domain
Free trial available, then plans start at $35/mo
Free trial: 14 days with full features, then $19/mo
| Tier | Resend | Mailgun | Sequenzy | Volume |
|---|---|---|---|---|
| Starter | $20/mo 50,000 emails/month, 10 domains, webhooks | $35/mo 50,000 emails/month, 5 days log retention, basic analytics | $19/mo 15,000 emails/month, all SaaS workflows, billing integration | 50K emails/month |
| Growth | $80/mo 200,000 emails/month, dedicated IP, priority support | $90/mo 100,000 emails/month, dedicated IP, 15 days log retention | $49/mo 50,000 emails/month, dedicated IP, advanced analytics | 100K-200K emails/month |
| Scale / Pro | Custom Custom volume, SLA, SSO | $350+/mo 500K+ emails/month, 30 days log retention, SLA, priority support | $149/mo 200,000 emails/month, SLA, SSO, custom onboarding | 500K+ emails/month |
Resend: Watch Out For
- !No marketing features, need a separate tool
- !Enterprise pricing not published
- !No SMTP relay or inbound email support
Mailgun: Watch Out For
- !Email validation (Mailgun Optimize) is a separate paid add-on
- !Log retention is limited on lower plans (only 5 days on Starter)
- !Dedicated IP costs extra on lower plans
- !IP pool management fees on some plans
Sequenzy: Watch Out For
- !Smaller SDK ecosystem
- !No email validation service
- !Free tier is a 14-day trial
Pricing Verdict: Resend offers better value for transactional email with simpler pricing and a superior developer experience. Mailgun is better value if you need email validation or inbound processing. Sequenzy is the best value for B2B SaaS teams needing lifecycle email, because at $19/mo you get billing-triggered workflows that would cost $100+ extra elsewhere.
Cost Comparison Note
Most SaaS teams need transactional and lifecycle email. Using Resend or Mailgun for delivery plus a separate lifecycle tool costs $100-250/mo combined. Sequenzy combines both at $19/mo for SaaS-specific use cases.
B2B SaaS Use Cases
How each platform handles the email workflows that matter most for B2B SaaS companies.
🎯 User Onboarding Sequences
Automated email sequences guiding new signups through activation.
Resend
Build onboarding logic in your code. Send each email via Resend API. React Email templates for consistency. All sequencing in your codebase.
Mailgun
Send onboarding emails via Mailgun API or SMTP. No built-in sequencing. Your application handles all timing and branching logic.
Sequenzy
Pre-built onboarding templates connected to billing. Trigger from signup, branch by plan type and engagement. Ready in minutes.
Verdict: Sequenzy wins with pre-built SaaS onboarding templates. Neither Resend nor Mailgun offers onboarding automation.
Real-World Example
A SaaS needs a 5-email onboarding sequence. Sequenzy provides a template. Resend and Mailgun require building everything from scratch.
Example subject line: Welcome to [App]. Here is your quickstart checklist.
🔔 Transactional Notifications
System emails like password resets, receipts, and alerts requiring instant delivery.
Resend
Purpose-built for this. Send via API with React Email templates. Sub-second delivery with comprehensive tracking.
Mailgun
Strong transactional delivery via API or SMTP relay. Flexible routing rules for complex notification systems. Proven at scale.
Sequenzy
Send transactional emails via API with SaaS-specific templates. Reliable delivery with billing data integration.
Verdict: Resend has the edge for transactional email with better DX and delivery speed. Mailgun is reliable with the added flexibility of SMTP relay. Sequenzy handles transactional but adds more value in lifecycle email.
Real-World Example
A SaaS sends 50K transactional emails daily. Resend offers the cleanest API. Mailgun offers SMTP for legacy systems.
Example subject line: Your password has been reset
💰 Trial-to-Paid Conversion
Strategic trial conversion emails tied to billing events.
Resend
Build conversion logic in your app. Send via Resend API at milestones. All trial tracking in your codebase.
Mailgun
Send trial emails via Mailgun API when your app detects milestones. No trial awareness built in.
Sequenzy
Purpose-built trial conversion connected to Stripe/Paddle. Pre-built templates for each trial stage.
Verdict: Sequenzy wins decisively. Native billing integration means automatic trial tracking. Both Resend and Mailgun require building everything from scratch.
Real-World Example
A SaaS wants different conversion emails based on engagement. Sequenzy does this automatically from billing data.
Example subject line: Your trial ends in 3 days.
💳 Payment Failed (Dunning)
Automated payment recovery emails to reduce involuntary churn.
Resend
Send dunning emails via Resend API from billing webhooks. Your app manages the retry schedule.
Mailgun
Send dunning emails via Mailgun API or SMTP from billing webhooks. No built-in dunning support.
Sequenzy
Dunning activates automatically from Stripe/Paddle payment failures. Escalating templates included. Auto-stops on success.
Verdict: Sequenzy dominates. Automatic detection and pre-built sequences. Resend and Mailgun both require custom development.
Real-World Example
A subscription SaaS needs 3 escalating dunning emails. Sequenzy handles this automatically.
Example subject line: Action required: your payment for [App] failed
🧹 Email Validation & List Cleaning
Verifying email addresses before sending to improve deliverability and reduce bounces.
Resend
Not available. Use a third-party validation service like ZeroBounce or NeverBounce.
Mailgun
Mailgun Optimize provides real-time and bulk email validation. Check addresses at signup or clean existing lists. Integrated directly into your sending workflow.
Sequenzy
Not available natively. Relies on bounce handling and suppression lists for list hygiene.
Verdict: Mailgun is the only platform here with built-in email validation. This is a significant advantage for maintaining list quality and deliverability.
Real-World Example
A SaaS with 50K signups per month wants to validate emails at registration to prevent bounces. Only Mailgun offers this built-in.
Example subject line: N/A (validation happens before sending)
🔄 Churn Prevention
Automated re-engagement emails for users showing declining activity.
Resend
Build churn detection in your app. Send re-engagement emails via Resend API. All logic in your codebase.
Mailgun
Send re-engagement emails via Mailgun when your app detects at-risk users. No built-in behavior tracking.
Sequenzy
Churn prevention combining product usage with billing data. Auto-identify users who downgrade or reduce usage. Pre-built win-back sequences.
Verdict: Sequenzy wins with billing-aware churn prevention. Neither Resend nor Mailgun offers any churn detection features.
Real-World Example
A SaaS wants to email inactive users with subscription context. Only Sequenzy combines behavior and billing data.
Example subject line: We noticed you have not logged in this week.
📥 Inbound Email Processing
Receiving and processing emails sent to your application.
Resend
Not supported. Need a separate service.
Mailgun
Full inbound routing with webhook parsing. Route emails to different endpoints based on recipient, domain, or content. Parse attachments and structured data.
Sequenzy
Not supported.
Verdict: Mailgun is the only option for inbound email processing. Neither Resend nor Sequenzy supports this.
Real-World Example
A SaaS needs to process reply emails for support tickets. Only Mailgun handles this natively.
Example subject line: Re: Your support ticket #1234
📈 Upsell & Expansion
Targeted upgrade emails based on usage and plan data.
Resend
Your app detects opportunities and sends via Resend API. React Email templates for upgrade messages.
Mailgun
Send upgrade emails via Mailgun when your app identifies opportunities. No built-in upsell support.
Sequenzy
Automatic triggers when users approach plan limits. Sequences personalized by plan and billing history.
Verdict: Sequenzy is purpose-built for expansion revenue with native billing data. Neither Resend nor Mailgun has upsell features.
Real-World Example
A SaaS wants to upsell users hitting limits. Sequenzy automates this from billing data.
Example subject line: You have used 90% of your storage quota
The Bigger Picture
Resend and Mailgun excel at email delivery but lack SaaS lifecycle features. For B2B SaaS teams needing billing-triggered workflows, Sequenzy handles the full spectrum with native billing integrations that neither offers.
Automation Capabilities
Email automation is critical for B2B SaaS. Here is how Resend, Mailgun, and Sequenzy compare.
| Capability | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| Visual workflow builder | No No workflow builder | No No workflow builder | Yes Visual builder with SaaS templates |
| Event-based triggers | No Your app calls the API | No Your app calls the API | Yes Product + billing events |
| Drip sequences | No Not available | No Not available | Yes Pre-built SaaS lifecycle drips |
| Conditional branching | No Build in your code | No Build in your code | Yes Branch by plan, MRR, trial status |
| Email routing | No Basic domain routing | Yes Flexible inbound routing rules | No Standard sending only |
| Goal tracking | No Not available | No Not available | Yes Auto-remove on billing events |
| Dynamic content | Yes React components with props | Yes Recipient variables in templates | Yes Dynamic content with billing data |
API & Developer Experience
For B2B SaaS teams, the API quality directly impacts how fast you can integrate and iterate on email.
Resend API
- SDKs: Node.js, Python, Go, Ruby, PHP, Java, Elixir
- Docs: 10/10
- Webhooks: HMAC-signed webhooks with retry logic for all email events
- Rate Limit: 100 requests/second on Pro
- Batch: Batch API for multiple recipients in one call
Mailgun API
- SDKs: Python, Ruby, Java, C#, Go, PHP, Node.js
- Docs: 6/10
- Webhooks: Webhook events for delivery, opens, clicks, bounces. Configurable retry.
- Rate Limit: Varies by plan, generally generous for paid plans
- Batch: Batch sending via recipient variables in a single API call
Sequenzy API
- SDKs: Node.js (official), Python (official), REST API for all languages
- Docs: 8/10
- Webhooks: Email events plus billing events with retry logic.
- Rate Limit: 50 requests/second, higher on Scale
- Batch: Batch sending with per-recipient personalization
Resend Code Example
import { Resend } from "resend";
import { WelcomeEmail } from "./emails/welcome";
const resend = new Resend("re_your_api_key");
await resend.emails.send({
from: "Acme <hello@acme.com>",
to: "user@company.com",
subject: "Welcome to Acme",
react: WelcomeEmail({ firstName: "Sarah" }),
});Mailgun Code Example
const formData = require("form-data");
const Mailgun = require("mailgun.js");
const mg = new Mailgun(formData);
const client = mg.client({
username: "api",
key: "your-api-key",
});
await client.messages.create("acme.com", {
from: "Acme <hello@acme.com>",
to: ["user@company.com"],
subject: "Welcome to Acme",
template: "welcome",
"h:X-Mailgun-Variables": JSON.stringify({
firstName: "Sarah",
}),
});Sequenzy Code Example
import { Sequenzy } from "sequenzy";
const sq = new Sequenzy("sq_your_api_key");
await sq.subscribers.add({
email: "user@company.com",
firstName: "Sarah",
stripeCustomerId: "cus_abc123",
});
await sq.sequences.trigger({
email: "user@company.com",
sequence: "trial_onboarding",
});Email Deliverability Comparison
Your emails are useless if they do not reach the inbox. Here is how all three platforms handle deliverability.
| Factor | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| Infrastructure | Custom-built with AWS-backed sending | Sinch-backed infrastructure with global sending nodes | Managed infrastructure with SaaS-only pools |
| Inbox Placement Rate | ~96-98% (estimated) | ~92-96% (varies by shared pool) | ~96-98% (SaaS-only pools help) |
| Dedicated IP | Available on Pro ($80/mo) with auto-warmup | Available on Scale ($90/mo) | Available on Growth ($49/mo) |
| Auth Protocols | SPF, DKIM, DMARC, Custom Return-Path | SPF, DKIM, DMARC, Custom tracking domain | SPF, DKIM, DMARC, Custom Return-Path |
| IP Warmup | Automated warmup on dedicated IPs | Manual warmup with volume guidelines | Guided warmup with volume recommendations |
| Email Validation | Not available | Mailgun Optimize for real-time and bulk validation | Not available |
Resend generally has stronger deliverability than Mailgun due to more careful sender vetting. Mailgun shared IP reputation has varied, making dedicated IP more important. Mailgun Optimize email validation can help improve deliverability proactively. Sequenzy benefits from SaaS-only sender pools.
Integration Ecosystem
Resend has ~15 integrations, Mailgun has ~50, and Sequenzy has ~25. Here is how they compare across key B2B SaaS categories.
Payment & Billing
| Service | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| Stripe | Yes (API Only) | Yes (API Only) | Yes (Native) |
| Paddle | Yes (API Only) | Yes (API Only) | Yes (Native) |
| LemonSqueezy | Yes (API Only) | Yes (API Only) | Yes (Native) |
CRM
| Service | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| HubSpot | No (API Only) | Yes (3rd Party) | Yes (Official) |
| Salesforce | No (API Only) | Yes (3rd Party) | Yes (3rd Party) |
Product Analytics
| Service | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| Segment | No (API Only) | Yes (3rd Party) | Yes (Official) |
| Mixpanel | No (None) | No (None) | Yes (3rd Party) |
Automation & Workflow
| Service | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| Zapier | Yes (Official) | Yes (Official) | Yes (Official) |
| Make (Integromat) | Yes (3rd Party) | Yes (Official) | Yes (Official) |
| n8n | Yes (3rd Party) | Yes (Official) | Yes (3rd Party) |
Development Frameworks
| Service | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| Next.js | Yes (Native) | Yes (API Only) | Yes (API Only) |
| Django/Flask | Yes (Official) | Yes (Official) | Yes (Official) |
| Rails | Yes (Official) | Yes (Official) | Yes (API Only) |
Analytics & Reporting
What data you can track and how each platform helps you measure email performance.
| Metric | Resend | Mailgun | Sequenzy |
|---|---|---|---|
| Open rate tracking | Per-email via webhooks | Per-email tracking with analytics | Per-campaign and per-sequence |
| Click tracking | Click tracking via webhooks | Click tracking with URL rewriting | Link-level with conversion attribution |
| Bounce tracking | Detailed classification with suppression | Bounce handling with suppression | Bounce tracking with payment context |
| Unsubscribe tracking | Via webhooks | Unsubscribe tracking with management | Built-in with preference center |
| Revenue attribution | Not available | Not available | Native MRR impact per sequence |
| Dashboard | Minimal, most data via API | Analytics dashboard with charts | SaaS-focused with MRR metrics |
| Log retention | Standard retention | 5-30 days depending on plan | 30+ days on all plans |
Resend: Unique Features
- + Provider-level delivery breakdown
- + Real-time delivery logs
- + Webhook event replay
- + Domain health monitoring
Mailgun: Unique Features
- + Mailgun Optimize inbox placement testing
- + Email validation analytics
- + Inbound email routing analytics
- + Tag-based analytics for categorization
Sequenzy: Unique Features
- + MRR impact per email sequence
- + Trial conversion rate tracking
- + Dunning recovery rate dashboard
- + Churn prevention metrics
- + Subscriber lifecycle overview
Pros & Cons
Resend
Pros
- + Best-in-class developer experience and API design
- + React Email for building templates as components
- + Excellent documentation with interactive examples
- + Official SDKs in 7 languages
- + HMAC-signed webhooks with retry
- + Clean volume-based pricing
- + Strong deliverability with careful sender vetting
- + Fast transactional delivery
Cons
- - No SMTP relay
- - No inbound email processing
- - No email validation service
- - No marketing automation
- - Younger platform with shorter track record
- - Analytics are minimal
- - Enterprise pricing not published
- - No SaaS lifecycle features
Mailgun
Pros
- + Full SMTP relay with flexible routing
- + Inbound email processing with webhook parsing
- + Built-in email validation (Mailgun Optimize)
- + Proven at scale with years of operation
- + Flexible routing rules for complex workflows
- + Tag-based analytics for email categorization
- + Action Mailer support for Rails apps
- + Batch sending with recipient variables
Cons
- - API design feels dated compared to Resend
- - Documentation can be hard to navigate
- - SDKs feel less polished
- - Shared IP reputation can be inconsistent
- - Log retention limited on lower plans (5 days)
- - Pricing is higher than Resend for similar volume
- - Multiple ownership changes (Rackspace, Sinch) create uncertainty
- - No SaaS lifecycle or billing integration features
Who Should Use What?
Specific recommendations based on your company type and needs.
Early-stage SaaS
Pre-PMF startup needing basic email infrastructure.
Sequenzy at $19/mo gives you transactional email plus SaaS lifecycle sequences and billing integration from day one.
Developer tool with clean API needs
Engineering team wanting the best possible API experience.
Resend has the best API design, docs, and DX in the market. React Email templates integrate naturally into modern development workflows.
SaaS needing email validation
High-volume signups where you need to validate emails at registration.
Mailgun Optimize provides real-time email validation built into your sending platform. Neither Resend nor Sequenzy offers this.
Product-led growth SaaS
Self-serve signups, trials, and billing-aware lifecycle email.
Sequenzy connects to Stripe/Paddle for automatic trial conversion, dunning, and churn prevention without custom code.
SaaS with inbound email needs
Your product processes incoming emails.
Mailgun has full inbound email routing and parsing. Neither Resend nor Sequenzy supports inbound.
Rails-based SaaS
Ruby on Rails application wanting SMTP with Action Mailer.
Mailgun has excellent Rails integration with Action Mailer support and SMTP relay. Resend requires API-based sending.
Bootstrapped SaaS on a budget
Need transactional and lifecycle email at the lowest cost.
Sequenzy at $19-49/mo combines transactional and lifecycle email. Mailgun for transactional plus a marketing tool costs $120+ combined.
Churn-focused SaaS
Reducing churn through dunning and re-engagement is the priority.
Sequenzy has native billing integration for automatic dunning and churn prevention with real subscription data.
Migration Guide
Migrating from Resend to Mailgun
Steps
- 1. Set up Mailgun account and verify domain
- 2. Convert React Email templates to Mailgun Handlebars templates
- 3. Update API calls from Resend SDK to Mailgun SDK
- 4. Configure webhook endpoints
- 5. Set up SMTP relay if needed
- 6. Test all email flows
- 7. Migrate traffic gradually
Watch Out For
- ! React Email templates need conversion to Handlebars
- ! Mailgun SDK conventions differ significantly
- ! Webhook event names and payloads are different
- ! Log retention may be shorter on lower Mailgun plans
Migrating from Mailgun to Resend
Steps
- 1. Set up Resend account and verify domain
- 2. Convert Mailgun templates to React Email or HTML
- 3. Update API calls from Mailgun SDK to Resend SDK
- 4. Replace SMTP relay with API calls
- 5. Migrate webhook endpoints
- 6. Test all email flows
- 7. Cut over and monitor
Watch Out For
- ! SMTP-dependent systems need API migration
- ! Inbound email processing needs a replacement service
- ! Email validation (Mailgun Optimize) needs a replacement
- ! Historical data will not transfer
The Bottom Line
Choose Resend if...
- ✓ You want the best developer experience and API design
- ✓ You build email templates in React
- ✓ You need clean, simple transactional email
- ✓ You value excellent documentation and SDKs
- ✓ You do not need SMTP, inbound email, or email validation
- ✓ Deliverability with careful sender vetting matters to you
Choose Mailgun if...
- ✓ You need SMTP relay for legacy systems or frameworks
- ✓ You need inbound email processing
- ✓ You want built-in email validation
- ✓ You use Ruby on Rails with Action Mailer
- ✓ You need flexible email routing rules
- ✓ You want a platform with 10+ years of operation
Frequently Asked Questions
Is Resend better than Mailgun?
For developer experience, API design, and documentation, Resend is significantly better. For feature breadth (SMTP, inbound email, email validation), Mailgun offers more. If you primarily need a clean transactional email API, Resend is the better choice. If you need SMTP relay, inbound processing, or built-in validation, Mailgun is stronger.
Does Mailgun have better deliverability than Resend?
Generally no. Resend tends to have stronger deliverability due to more careful sender vetting. Mailgun shared IP pools have varied in quality over the years. A dedicated IP with Mailgun helps significantly. Both platforms support SPF, DKIM, and DMARC.
Can Mailgun validate email addresses?
Yes. Mailgun Optimize provides real-time and bulk email validation as a paid add-on. This is a unique advantage over Resend and most other email APIs. It can check emails at registration to reduce bounces and improve deliverability.
Does Resend support SMTP?
No, Resend is API-only. If you need SMTP relay for legacy applications, WordPress, or hardware devices, Mailgun supports SMTP natively. You could also use both: Resend API for new code and Mailgun SMTP for legacy systems.
Which is cheaper: Resend or Mailgun?
Resend is generally cheaper. Resend starts at $20/mo for 50K emails. Mailgun starts at $35/mo for 50K emails. Resend also has a more generous free plan (3,000 emails/month vs. a limited trial). Sequenzy starts at $19/mo with lifecycle features included.
Has Mailgun changed ownership?
Yes. Mailgun started as a Rackspace project, became independent, and was acquired by Sinch in 2021. Multiple ownership changes have concerned some users about long-term product direction, though the service continues to operate reliably.