Choosing a transactional email provider is one of those infrastructure decisions that's easy to get wrong the first time. The differences between services aren't always obvious from pricing pages, and the factors that matter most - deliverability, support responsiveness, data residency - are hard to evaluate until you're already integrated.
This article gives you a factual, side-by-side comparison of four services: AhaSend, SendGrid, Resend, and Mailgun. It covers pricing, infrastructure, developer experience, and a dimension that most comparison articles skip entirely - where your data actually lives.
A quick overview
SendGrid is the oldest and now owned by Twilio. It started as a transactional email API and grew into a full platform covering both transactional and marketing email. The platform is extensive, pricing is split across two separate products (Email API and Marketing Campaigns), and the free tier was changed from a permanent plan to a 60-day trial.
Resend is the newest entrant, built with a strong developer-experience focus. It's popular in the React and Next.js ecosystem. Data is processed through US infrastructure.
Mailgun is a long-standing developer-focused API, now owned by Sinch. It supports both US and EU data regions. Its free tier is limited to 100 emails per day.
AhaSend is a European transactional email service built on KumoMTA, incorporated in the Netherlands, with ISO27001 certification pending, and operates under GDPR. It focuses exclusively on transactional email, with a developer-first API, official SDKs, SMTP relay, and a feature set built around deliverability and compliance.
Pricing comparison
Pricing as of April 2026.
| AhaSend | SendGrid | Resend | Mailgun | |
|---|---|---|---|---|
| Free tier | 1,000 emails/mo, permanent | 100 emails/day trial | 3,000 emails/mo, permanent | 100 emails/day |
| Entry paid plan | €10/mo (25,000 emails) | $19.95/mo (50,000 emails) | $20/mo (50,000 emails) | $15/mo (10,000 emails) |
| Full plan | €80/mo (100,000 emails) | $89.95/mo (100,000 emails) | $90/mo (100,000 emails) | $90/mo (100,000 emails) |
| Overage rate | €0.45/1,000 (max $0.50 USD) | variable, plan-dependent | $0.90/1,000 | $1.10–$1.80/1,000 |
| Dedicated IP | Accessible at 100k/mo (Pro), included at 300k+ | Add-on from $30/mo | Add-on from $30/mo (Scale+) | Included on Foundation+, add-on $59/IP/mo |
A few things worth noting on pricing:
SendGrid's free tier changed in early 2025. New accounts now get a 60-day timed trial rather than a permanent free plan. If you want a free tier you can actually build on without a clock running, the other three options are better starting points.
Mailgun's entry plan starts at $15/month for 10,000 emails. The Scale plan at $90/month for 100,000 emails is the relevant full-plan comparison, which puts it on par with AhaSend Max and Resend Scale on volume but at a higher overage rate. Overage rates on Mailgun are the highest of the four.
Resend and AhaSend are closely matched on full-plan pricing. AhaSend prices in euros but also offers USD pricing, which is a natural fit for European businesses billing in euros. Where they diverge is on overage: Resend charges $0.90 per 1,000 additional emails, while AhaSend's overage is €0.45 (max $0.50 USD) - roughly half the cost.
Infrastructure and deliverability
All four services offer high-quality shared delivery infrastructure. The meaningful differences are in how they manage shared pools and when dedicated IPs become available. If you want to understand what poor infrastructure actually costs your business, we wrote about that here.
SendGrid's shared infrastructure is extensive but has historically attracted complaints in user reviews about shared IP reputation degradation. Dedicated IPs are available as an add-on on paid plans.
Resend actively manages its shared IPs and positions them as high quality for most senders. Dedicated IPs are available on the Scale plan for senders exceeding 500 emails per day.
Mailgun includes a dedicated IP on its Foundation plan and above, making it one of the earlier access points for dedicated sending infrastructure. Additional IPs cost $59/month each.
AhaSend runs high-quality shared delivery tiers for most senders, with dedicated IP access opening at 100,000 emails per month on the Pro plan and one dedicated IP included in the Max plan. The infrastructure runs on KumoMTA, the same engine used by some of the largest commercial senders globally, and is built for high availability with geo-redundant architecture across Europe.
Developer experience
All four services offer REST APIs, SMTP relay, and webhook support. The differences are in SDK quality, documentation, and how quickly you can get from signup to first send.
Resend has a strong developer experience reputation, particularly in the React and Next.js ecosystem. Its TypeScript SDK is well-regarded and documentation is clean. That said, its focus is narrow - if you're not building in the React ecosystem, the differentiation is less meaningful, and the platform lacks some of the operational depth that more established services offer.
SendGrid has the most comprehensive API coverage and the widest range of official SDKs, but the platform's age shows in places. The dashboard can be complex to navigate, and the split between Email API and Marketing Campaigns products creates confusion for new users.
Mailgun has a solid API with good documentation and detailed delivery logs. It doesn't have the same modern developer-experience polish as Resend, but it's reliable and well-understood.
AhaSend offers official SDKs in Go, with JavaScript/TypeScript and Ruby in progress. The API is REST and SMTP, with a full Management API, sandbox mode, scoped API keys, inbound email routing, and signed webhook endpoints available across all paid plans. Setup to first send is documented as under five minutes. One feature worth calling out specifically is subaccounts - AhaSend supports isolated subaccount environments within a single account, which is particularly useful for agencies, hosting providers, or SaaS platforms managing email infrastructure on behalf of multiple clients. This is uncommon in the transactional email space.
Data residency and GDPR
This is the dimension most comparison articles skip, and for European businesses it's increasingly the deciding factor.
SendGrid is a US company (Twilio) with US-based infrastructure. Customer data is processed in the United States. GDPR compliance is possible through contractual means, but data leaves European jurisdiction.
Resend is a US company with US-based infrastructure. The same applies.
Mailgun is owned by Sinch (Swedish company) and does offer an EU data region as a sending option. This is a meaningful differentiator compared to SendGrid and Resend for European senders who need data to stay in the EU.
AhaSend is incorporated in the Netherlands as AhaSend B.V. and operates exclusively on European infrastructure. Data stays in Europe. GDPR compliance is built into the product, not added as a contractual layer. For transparency: AhaSend does offer an optional US egress node for customers who need it - email may transit this node for delivery purposes, but is never stored outside Europe. For European businesses operating under GDPR, this removes a layer of legal complexity and vendor dependency risk.
Summary: who should use what
SendGrid makes sense for high-volume senders who are already integrated, who need the full marketing + transactional combination on one platform, or who are building on US infrastructure and have no data residency requirements.
Resend makes sense for developer teams working in the React/Next.js ecosystem who prioritize developer experience and clean API design, and who are comfortable with US-based data processing.
Mailgun makes sense for developers who want a proven, stable API with predictable pricing and don't need a modern developer experience, or who need US/EU region flexibility without moving to a fully European provider.
AhaSend makes sense for European businesses and developers who want their transactional email infrastructure to stay in Europe - whether for GDPR compliance, sovereignty reasons, or simply because they prefer working with a European vendor in their timezone. It's also well-suited to developers who value a focused, transactional-only product without the complexity of a combined marketing platform. And on pricing, particularly at scale, AhaSend is hard to ignore: with the lowest overage rate of the four and a straightforward plan structure, the cost difference compounds quickly as volume grows.
Looking for a deeper comparison? See our dedicated pages for AhaSend vs SendGrid and AhaSend vs Mailgun.