Mailgun

What Mailgun actually is

Mailgun is a transactional email API with a deliverability suite attached, built for developers who send mail from applications rather than from a marketing console. It has been around since 2010 — the technology started inside Rackspace, was spun out as Mailgun Technologies (Delaware) in 2017, traded hands through Pathwire, and was acquired by Sinch in December 2021 for a reported USD 100 million. Today it sits in Sinch's developer and email business unit, run out of San Antonio, Texas, while the parent is listed on Nasdaq Stockholm. Corporate ownership matters here: it is why the legal entity is American, the parent is Swedish, and EU customers end up asking pointed questions about the CLOUD Act.

The product surface is what you would expect from a mature ESP: RESTful email APIs and SMTP relay, mailing lists, recipient variables, custom sending domains, tracking, analytics, webhooks, bounce classification, plus two adjacencies that set Mailgun apart from pure senders. The first is inbound email routing — parse incoming mail into structured JSON via HTTP POST, available on every plan (one inbound route on Free, five on Basic, full access from Foundation). The second is the Optimize and Inspect families: email validation, deliverability tools (Inbox Placement, reputation monitoring), and email preview testing across 100+ clients sold as separate products from $99 per month. If you are building a product where users reply to notification emails, the inbound parsing is a genuine reason to shortlist this vendor.

Scale is not in question. Mailgun states it sends on the order of 650 billion emails a year, runs on Google Cloud Platform, and lists customers like Microsoft, Lyft, and Etsy. Enterprise claims include throughput SLAs up to 72 million message requests per hour and guaranteed attempted delivery of 15 million messages within five minutes. Those are contract-tier numbers, but they tell you the pipeline is engineered for volume.

Pricing: what you really pay

Public pricing is four tiers, and it is genuinely readable. Free: $0 per month with 100 emails per day, one custom sending domain, two API keys, one inbound route, and one day of log retention. Basic: from $15 per month with 10,000 emails included, no daily limit, five inbound routes, and overage from $1.80 per 1,000 emails. Foundation: free for the first month, then $35 per month with 50,000 emails included, 1,000 custom sending domains, the email template builder and API, five days of log retention, full inbound routing, and overage from $1.30 per 1,000. Scale: free for the first month, then $90 per month with 100,000 emails included, SAML SSO, 5,000 email validations, dedicated IP pools, send-time optimisation, live phone and chat support, 30 days of log retention, and overage from $1.10 per 1,000. Extra validations cost from $1.20 per 100 on Basic and Foundation and from $0.80 per 100 on Scale.

Three pricing realities deserve flagging. First, the free plan is not a trial — the FAQ is explicit that it has no time limit — so the claim you sometimes see of "100 emails/day free for 3 months" is wrong; the 30-day free access applies to the paid tiers' first month. Second, log retention is the quiet upsell driver: one day on Free and Basic is short enough that debugging a delivery issue a week later is impossible without shipping logs yourself. Third, dedicated IPs are a volume-gated add-on — the comparison table shows access from 50k volumes and inclusion at higher volumes, and third-party listings put extra dedicated IPs at around $59 per IP per month. If your deliverability plan depends on a dedicated IP, price that in separately.

Billing is monthly, prorated on signup, with overages billed in arrears — so a traffic spike shows up on next month's invoice, not this one. We like the transparency of published overage rates; we like less that the slider prices and overage rates do not reproduce each other exactly, which makes the effective per-thousand cost at high overage worth calculating before you commit.

Performance & infrastructure

Mailgun runs on Google Cloud Platform and publishes a real service level agreement rather than a marketing uptime number: the API, SMTP, and outbound delivery services are guaranteed to be available 99.99% of the time in any given monthly billing period, excluding maintenance. The remedy is credits — per the SLA, 5% of the monthly service fee per 30 minutes of unavailability after an initial threshold, capped at 50% of monthly fees, with claims due within 30 days. Note the scope: Mailgun Optimize deliverability tools are excluded from that guarantee. This is one of the few ESPs where we could point at a credit-backed number, so we score it well on SLA honesty.

Regional sending is a genuine feature: accounts can send from US or EU regions (the EU region is Ireland), which is the practical answer to GDPR data-residency questions even though the legal entity is American. Compliance paperwork covers GDPR, HIPAA, SOC I and II, and ISO 27001. Deliverability tooling is the second layer: SPF, DKIM, DMARC, BIMI support, automated dedicated IP warm-up, suppression management, bounce classification, and webhooks for everything. For teams that live in dashboards, the analytics and event tracking are more detailed than the cheaper competition.

We have no independent benchmark of Mailgun's pipeline — our own sysbench/fio/iperf3 runs cover compute hosts, not ESPs — so treat throughput figures as vendor-stated. What we can verify is the operational surface: a status page listing the covered services, SDKs across the common languages, and documentation that explains the sending stack end to end. In our view the docs are the strongest ecosystem asset here.

Where it falls short

Support is tiered in a way that hurts exactly the customers who need help most. Free and Basic get ticket support; chat and live phone support arrive only on Scale at $90 per month. Sinch ownership has drawn community criticism about support responsiveness since the acquisition, and while we cannot quantify that, the plan structure itself confirms the direction: human help is a premium feature.

Cost escalates with volume more aggressively than the headline prices suggest. At 100,000 emails per month the arithmetic on our reading of the pricing page is Foundation at $35 plus overage versus Scale at $90 — worth working out before you auto-upgrade. Validation is an add-on below Scale, one user per account on Free, and template tooling only exists from Foundation up. Small teams will feel nickel-and-dimed by the feature gates even though the base prices look friendly.

The 100 emails per day free cap is honest but tiny — roughly 3,000 a month, with one sending domain and one user. Fine for a side project's password resets; useless for anything with real sign-up volume.

Jurisdiction is the strategic caveat. The parent is Swedish-listed, the operating entity is American, and EU-region sending keeps data in Ireland — but the corporate structure does not eliminate US legal reach, and privacy-focused buyers in Europe should read the DPA and decide for themselves. Several EU-focused competitors exist precisely on this axis.

Who should pick this

Our pick for developers who want inbound email parsing alongside transactional sending. Building a support tool where customers reply to tickets-by-email, or a service that processes inbound mail into webhooks? Mailgun's inbound routing on every plan, mature parsing, and per-event webhooks are the cleanest developer experience in this category in our view.

Also a solid pick for growing SaaS teams that expect to need dedicated IPs and deliverability tooling later: the path from $15 Basic to Scale with IP pools and validation is coherent, and the SLA is real.

We would not pick Mailgun for: budget-conscious bulk senders (cheaper per-thousand options exist), teams that need chat/phone support at low volume, organisations requiring non-US corporate jurisdiction, or anyone satisfied with a handful of sends a day who would rather not pay for log retention.

Key takeaways

• Mature transactional email API (founded 2010, Sinch-owned since 2021) with inbound email parsing on every plan — the standout developer feature.
• Published plans: Free 100 emails/day at $0; Basic from $15/mo (10,000 emails); Foundation $35/mo (50,000); Scale $90/mo (100,000), with overage from $1.10–$1.80 per 1,000 emails.
• The free plan is permanent, not a 3-month trial; the 30-day free access applies to the first month of Foundation and Scale.
• Credit-backed 99.99% availability SLA on API, SMTP, and outbound delivery — one of the few in this category; Optimize products are excluded.
• Log retention is the gate to watch: one day on Free/Basic, 30 days on Scale; dedicated IPs cost extra below high volumes.
• Strong fit for app-driven transactional mail and inbound processing; weaker fit for budget bulk sending or EU-jurisdiction-sensitive buyers.

Sources

• https://www.mailgun.com/pricing/
• https://www.mailgun.com/legal/sla
• https://mailgun.com/ai-info
• https://www.saasemailplatforms.com/compare/mailgun-vs-sendgrid
• https://sota.io/blog/mailgun-eu-alternative-2026-cloud-act-gdpr-sinch-transactional-email