As of 2 Nov 2026, the panel rates Mailgun 2/5 and Postmark 3/5 in Transactional Email. Weighted by what each judge cares about, 2 of the 6 judges pick Mailgun and 4 pick Postmark. Postmark scores higher on 7 of 7 criteria (Sending API, SMTP & developer experience, Deliverability & sender reputation, Reliability, accounts & support, plus 4 more). Provenance — Mailgun: Rest of world; Postmark: Rest of world. Ratings are the AI panel’s opinion, formed from public evidence: how scores are made.
Postmark's widest leads are the sending API (7.0 to 4.0, six judges lean Postmark) and deliverability (7.5 to 4.5, four lean Postmark, two tie); its means also lead on observability, reliability and accounts, sovereignty and pricing transparency. Mailgun draws more judge leans on data and security, sovereignty and pricing transparency — three to two with one tie on each — even where Postmark's means run higher. Weighted totals split four to two: the developer (6.8 to 6.4), agency lead (6.4 to 6.2), data protection officer (5.8 to 0) and skeptic (6.2 to 0) carry Postmark; the platform engineer (6.5 to 6.4) and ecommerce operator (6.6 to 6.2) carry Mailgun. On sovereignty, Mailgun's pages show a published data processing agreement with standard contractual clauses under Swedish law and a selectable EU region, beside Texas-law contracting; Postmark's show Illinois law and United States storage, with no EU hosting region found on the captured pages.
Choose Mailgun if
Your team follows the bench lean on data and security, where three judges lean Mailgun, two lean Postmark and one ties.
You contract under EU terms: Mailgun's captured pages publish a data processing agreement with standard contractual clauses under Swedish law and an EU region the customer must select, and sovereignty leans Mailgun three to two.
You need a written uptime commitment: Mailgun's pages carry a 99.99% monthly uptime guarantee, while we found no SLA information on Postmark's captured pages.
Your reviewers match the platform engineer or ecommerce operator, whose weighted totals read 6.5 to 6.4 and 6.6 to 6.2 for Mailgun.
You send low volumes first: Mailgun's pages list a free tier at 100 emails/day.
Choose Postmark if
You build against the sending API first: Postmark's mean is 7.0 to Mailgun's 4.0, with six judges leaning Postmark.
Deliverability decides the purchase: Postmark's mean is 7.5 to 4.5 (four judges lean Postmark, two tie), resting on manual vetting of new senders, free custom Return-Path and DKIM, and separate infrastructure for transactional and broadcast traffic.
You compare starting prices across pages: Mailgun's captured pages give different figures for the starting price — $15/month for 10,000 emails versus Foundation at $35/mo — while Postmark's pricing transparency mean is 7.0 to 5.2.
Your operations lean on webhooks: the reliability and accounts mean is 6.2 to 4.0 (three judges lean Postmark, three tie), with strong webhooks and redundancy cited in the verdict.
Your operations run in the United States: Postmark's captured pages state personal information is stored in AWS and Deft data centres in the United States.
Read this comparison as one judge. Each weighs the same scores by what they care about.
The Platform Engineer
Platform engineer at a fintech in Frankfurt whose customers sign in with a one-time code sent by email, so a delay of three minutes is an outage. Is on call for it. Reads the status page history before the feature list, wants the SLA in writing with credits, mail queued and retried during an incident, delivery latency per mailbox provider, alerts on bounce spikes, and scoped API keys that can be rotated without a deploy.
Mailgun
This judge's pick
Postmark
Criterion by criterion
Sending API, SMTP & developer experience
Mailgun
A documented REST API and SMTP relay on ports 25, 465 and 587, official SDKs for Go, Node, PHP, Java, Ruby, Python and C#, batch sending to 1,000 recipients, scheduling, a sandbox domain, inbound mail parsed to UTF-8 JSON, and quick-start guides per language. We found no public information on rate limits, idempotency keys, template versions, an OpenAPI specification or migration guides, so the reference stops short of what I want before wiring authentication mail into it.
Postmark
A REST API and an SMTP relay are both fully documented — host, port, token headers — with vendor-maintained libraries for TypeScript, Node, Python, Ruby, Rails, PHP,.NET and Java, framework guides for Laravel, Rails, Express, Django and Craft, templates with an API and template push, batch sending up to 500 messages with documented partial-failure semantics, a test-token mode, stated limits (10 MB per email, 50 recipients) and error codes in body and header, inbound email parsed to a webhook, an official CLI, and migration guides from six named competitors. We found no public information on idempotency keys, scheduled sending, template versioning, or a published API versioning and deprecation policy.
Deliverability & sender reputation
Mailgun
SPF, DKIM and DMARC, dedicated IPs with automated warm-up and pools, an acceptable-use policy enforced on bounce and complaint rates, automatic suppressions for bounces, complaints and unsubscribes, and deliverability experts around the clock. What holds it back for me: inbox placement testing, blocklist and spam-trap monitoring sit in Mailgun Optimize, priced separately, and we found no public information on published delivery times or inbox rates per mailbox provider, so I cannot verify my login codes arrive quickly.
Postmark
Every sender is manually vetted, SPF/DKIM/DMARC are guided with a free custom Return-Path and DKIM domain, transactional and broadcast traffic ride completely separate infrastructure including IP ranges, and dedicated IPs come with Postmark-managed warm-up plus automatic overflow to the shared pool; feedback loops, reverse DNS and blocklist monitoring with resolution attempts are handled by the vendor, DMARC digests exist as a paid add-on, and delivery times per mailbox provider are published on the Time to Inbox and status pages over a 30-60 day window. We found no public information on BIMI or custom tracking domains, a stated position on the Gmail and Yahoo bulk-sender requirements, inbox placement testing, or access to deliverability experts.
Message logs, events & webhooks
Mailgun
Logs searchable by recipient, subject, tag and message ID with retention tiered by plan at one, five or thirty days, an Events API returning the data in full, and webhooks for delivered, bounced, opened, clicked, complained and stored events — signed with HMAC-SHA256, retried automatically, filterable, and streamable to Splunk or Datadog. We found no public information on the retry schedule, the receiving server's raw answer per message, a read-only role for support staff, or alerts when bounce rates spike; the documented alerts cover blocklists and reputation.
Postmark
Message activity logs keep 45 days of full content by default (customizable 7 to 365), webhooks cover delivery, bounce, spam complaint, open, click, subscription change and inbound with a retry schedule spelled out attempt by attempt, per-event-type health tracking, a retries-remaining and a stable trace header, automatic pause after persistent failure, and a statistics endpoint with retry counts and response times; tags carry statistics, and a teammate or observer can view logs without edit rights.
Message data, retention & security
Mailgun
Message bodies kept up to seven days and metadata thirty days with the retention documented, recipient addresses hashed, AES-256 at rest, TLS 1.2 or higher in transit, two-factor, IP access management, SAML on the Scale plan, a third-party bug bounty, SOC 2 Type II and ISO 27001, plus features to block retrieval of content or delete it after delivery. The terms note mail can be delivered unencrypted when the receiving server has no TLS, and we found no public information on API key scopes, a customer-visible audit log, or turning open and click tracking off per stream or message.
Postmark
What is stored per message is documented — metadata, address, content — with 45-day default retention, open and link tracking switchable per message, two-factor authentication on every plan that the owner can enforce, IP allow-listing, separate server and account tokens, encryption at rest stated, a GDPR data-removal API, and a published DPA. Outbound TLS is opportunistic with an unencrypted fallback that the customer cannot control, and the terms of service reserve the right to internally use Messaging Content to train and improve the service; we found no public information on SSO, an audit log, or ISO 27001 for the platform itself.
Reliability, accounts & support
Mailgun
The SLA is in writing — 99.99% monthly for the API, SMTP and outbound delivery, 5% of the monthly fee back per thirty minutes of downtime, capped at 50%, claimed by ticket — plus a status page for unplanned interruptions, unlimited users with five roles on paid plans, and plugins for WordPress, Shopify and Heroku. We found no public information on status-page history, mail queued and retried during an outage, data-centre failover, sub-accounts with their own keys, response times per plan, or any delivery-latency commitment, which is what a login flow on call actually needs.
Postmark
Redundant data centres in multiple locations with geographic load balancing and N+2 redundancy are described, servers separate applications with their own tokens manageable by API and CLI, three roles plus per-server permissions include an observer who can review history, and there are WordPress, Zapier and Nodemailer integrations with guides for Laravel, Rails, Express, Django and Craft, plus migration guides and migration credit. We found no public information on an uptime SLA with service credits, incident history on the status page, support response times, or whether mail is queued and retried during an outage — and the terms provide the service as is with liability capped at three months of fees, which is what I would have to sign.
European sovereignty
Mailgun
The contracting entity shown for Mailgun is Mailgun Technologies, Inc. under Texas law, an EU region can be selected for sending, and the named hosting is US cloud providers — AWS, Rackspace, Softlayer and Google Cloud — while support, engagement and payment run through listed US services like Zendesk, Snowflake and Stripe. A published DPA with standard contractual clauses governed by Swedish law, the Swedish authority IMY named, and SOC 2 and ISO 27001 certifications count in its favour, but we found no public information on where messages, logs and account data are processed or whether the EU region covers them.
Postmark
The contracting entity is AC PM, LLC, an ActiveCampaign company governed by Illinois law, personal information is stored in US data centres on AWS and Deft, and use of the service consents to processing and storage in the United States and other countries. An Article 27 EU representative is appointed, a DPA with Standard Contractual Clauses governed by Irish law is published, EU-US Data Privacy Framework certification is claimed, and a sub-processor list with change notification exists — but we found no public information on an EU hosting region, so the whole sending chain including logs runs through the United States.
Pricing transparency
Mailgun
Four public tiers with volume, price and overage per thousand — free at 100 emails a day, $35/mo for 50,000, $90/mo for 100,000, overage from $1.30 and $1.10 — dedicated IPs at $59/IP/month, log retention stated per tier, a one-month self-service term and prices exclusive of VAT. The Optimize add-on is 'priced separately', Enterprise is a quote, and overage rates are quoted 'from' a floor, so a year's cost is close to computable but not exact.
Postmark
Every tier is public with its overage rate per thousand emails — free at $0.00/mo with 100 emails a month and no overages, Basic at $15.00/mo with extra emails at $1.80/1,000, Pro at $16.50/mo at $1.30/1,000, Platform at $18.00/mo at $1.20/1,000 — dedicated IPs at $50/month per IP with no setup fees, DMARC monitoring at $14/month per domain, custom activity retention starting at $5/month, 45-day retention per tier, no rollover of unused emails, and monthly plans that auto-renew until cancelled with no annual option. We found no public information on VAT treatment, and the captured pages do not state the monthly email allowance included in each paid tier.
Sovereignty, side by side
Dimension
Mailgun
Postmark
Legal entity
Not determined
Not determined
Hosting location
Not determined
Not determined
Hosting options
Not determined
Not determined
Open source
Not determined
Not determined
Data processing agreement
Not determined
Not determined
Transfer impact assessment
Not determined
Not determined
Facts, side by side
Only facts both products carry under the same definition — anything else would not be a fair row.
As of 2 Nov 2026, the panel rates Postmark higher: 3/5 against 2/5. Weighted by what each judge cares about, 2 of the 6 judges pick Mailgun and 4 pick Postmark. Which one fits depends on the criteria that matter to you; the table on this page shows both side by side, and each judge’s reading has its own page. Both were scored by the same AI bench under the same rubric, from public evidence only, as the methodology describes.
Is Mailgun or Postmark European?
Mailgun is not European by provenance (Rest of world). Postmark is not European by provenance (Rest of world). Provenance is read from each company’s own legal pages: who builds it and who owns it.
Where do Mailgun and Postmark store customer data?
Per the vendors’ own pages as captured — Mailgun: Default not stated; pages mention the US, the EU, United States and Europe. Postmark: its pages as captured do not say.
Do Mailgun and Postmark have a free plan?
As of 2 Nov 2026, both vendors’ own pages state a free plan. Each product page links the pricing page it was read from.