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 Skeptic
Has seen "99% deliverability" with no method behind it, "dedicated IPs" that shared a pool with bulk senders, "EU hosting" that covered the API endpoint but not the logs, and seven days of log retention discovered during an incident on day eight. Reads that a vendor is "trusted by thousands of developers" and asks how bounces are suppressed, what is stored per message, which entity signs the DPA — and what moving away would cost.
Mailgun
Postmark
This judge's pick
Criterion by criterion
Sending API, SMTP & developer experience
Mailgun
The captured pages document a REST API and an SMTP relay on ports 25, 465 and 587, official SDKs for Python, Ruby, PHP, Java, C#, Node.js and Go, batch sending of up to 1,000 personalized emails in one call, scheduled sending, a sandbox domain for test sends, and inbound routing parsed to UTF-8 JSON. We found no public information on idempotency keys, rate limits, an error-code reference, template versioning or a migration guide from named competitors, which keeps this short of the higher anchors.
Postmark
A documented REST API and SMTP relay, official libraries for TypeScript, Node, Python, Ruby, Rails, PHP,.NET and Java maintained by Postmark's own developers, a CLI, batch sending with limits stated (500 messages, 50 MB), a test token value that does not deliver, inbound email parsed to JSON and posted to a webhook, and migration guides from SendGrid, Mailgun, Amazon SES, SparkPost, Mailchimp Transactional and Resend. We found no public information on idempotency keys, scheduled sending, template versions or a documented template language, or an OpenAPI specification. Strong, quotable developer tooling — the gaps I just named are what keep it below the top band.
Deliverability & sender reputation
Mailgun
SPF, DKIM and DMARC support, automated recording of hard bounces, complaints and unsubscribes into a suppressions list, dedicated IPs with automated warm-up starting on the foundation plan, and a stated policy of enforcing bounce, complaint and list-sourcing rules are all documented, alongside seed-list inbox placement testing and access to deliverability experts. We found no public information on feedback loops, DMARC reports, a statement of compliance with the Gmail and Yahoo bulk-sender rules, or published delivery times — and blocklist monitoring and bounce classification sit in Mailgun Optimize, which the pricing pages say is priced separately.
Postmark
Guided SPF, DKIM and DMARC with a free custom return-path, every new sender manually vetted with pre-send anti-abuse blocking, transactional and broadcast traffic kept apart including IP ranges, dedicated IPs from 300,000 messages a month with Postmark-managed warm-up in three to six weeks, blacklist monitoring and feedback loops handled by them, and delivery times published on a Time to Inbox page for the major providers. We found no public information on compliance with the Gmail and Yahoo bulk-sender rules, custom tracking domains or BIMI, or inbox placement testing, and the published metrics cover delivery times only — no bounce rates per provider and no method beyond a 30–60 day window.
Message logs, events & webhooks
Mailgun
Logs are searchable by sender, recipient, subject, tag, list name and message ID, with retention stated per plan — from one day of log retention on the free and basic tiers to 30 days on Scale — message bodies kept up to seven days, and webhooks for delivered, bounced, opened, clicked, unsubscribed, complained and stored events signed with HMAC-SHA256 and retried automatically; events are also fetchable by API and can be forwarded to Splunk or Datadog. We found no public information on the raw SMTP response or rendered message per send, a documented retry schedule, alerts on bounce or complaint thresholds, or read-only roles for support staff.
Postmark
Seven webhook types including inbound, retried on a documented schedule (six attempts at 1, 5, 10, 10, 10 and 15 minutes) with a retries-remaining header and a stable trace header, per-event-type health checks that pause a failing event rather than the whole webhook, a webhook statistics endpoint, and forty-five days of full content history customisable from 7 to 365 days with statistics kept indefinitely.
Message data, retention & security
Mailgun
The pages document what is stored per message — bodies up to seven days, metadata thirty days, suppressions until removal — plus hashed recipient addresses, AES-256 encryption at rest, two-factor authentication, IP access management, SAML SSO, SOC 2 Type II and ISO 27001, a bug bounty, and APIs to search event data, suppressions and message content; staff may access message bodies for troubleshooting and that access is audited. Two things temper this: the terms say content may be transmitted even if the recipient does not also support TLS, resulting in an unencrypted transmission, and they reserve the vendor's right to view and use message routing data for general business purposes; we found no public information on switching off open and click tracking per stream or on API key scopes.
Postmark
The DPA lists what is processed per message — metadata, email address, message content — with retention stated and adjustable (45 days default, 7 to 365), open and click tracking switchable per message, a Data Removal API for recipient deletion, two-factor authentication on every plan including the free one, and cold data at rest encrypted with 2048-bit RSA in SOC 2 certified data centres. Outbound TLS is opportunistic with a fallback to unencrypted and Postmark states the customer cannot control or require it, and the terms grant a licence to internally use messaging content to train and improve the service — the exact clause I read every contract looking for. We found no public information on SSO, an audit log, or a vulnerability disclosure programme.
Reliability, accounts & support
Mailgun
There is a status page, a 99.99% monthly uptime guarantee covering API, SMTP and outbound delivery with credits of 5% of the monthly fee per thirty minutes of downtime capped at 50% and claimable by support ticket within thirty days, five user roles with unlimited users from Foundation upward, 24/7 support that varies by plan, and plugins for WordPress, Shopify, Heroku and many other named platforms. We found no public information on incident history, redundancy across data centres, queueing of mail during outages, sub-accounts, or support response times per plan.
Postmark
Servers per application with per-plan limits and API management, three roles (Owner, Admin, Teammate) with a documented permission matrix, redundant data centres in multiple locations with N+2 and geographic load balancing, WordPress, Zapier and Nodemailer integrations, and a success team that never charges extra for premium support. The status page carries real-time delivery metrics, but we found no public information on an uptime SLA, service credits, incident history or post-mortems, mail queueing during outages, or support response times.
European sovereignty
Mailgun
An EU region can be selected for sending, a data processing agreement is published carrying the 2021 standard contractual clauses with Swedish governing law and the Swedish authority as supervisor, and the terms name Mailgun Technologies, Inc. under Texas law as the contracting entity for Mailgun, with Mailjet SAS under French law as an alternative — the parent being Sinch AB of Stockholm. We found no public information on where messages, logs and account data are stored, on the locations of the named subprocessors, or on what the EU region covers beyond sending, and transfers rely on the EU-US Data Privacy Framework certified for the US entity.
Postmark
The contracting entity is AC PM, LLC, an ActiveCampaign company governed by Illinois law, storage is in AWS and Deft data centres, and users consent to processing and storage in the United States and other countries; the DPA leans on the EU-U.S. Data Privacy Framework and Standard Contractual Clauses, so transfers out of the EEA are the stated path and no EU hosting region appears in any capture. An Article 27 representative in Kiel, published SCC modules governed by Irish law, and a sub-processor list with change notification are real, but they are safeguards on a US chain, not European processing.
Pricing transparency
Mailgun
Every self-service tier is public with volume and overage — free at 100 emails/day, paid beginning at $15/month for 10,000 emails, Foundation at $35/mo with 50,000 emails/mo and 'from $1.30 / 1,000 emails', Scale at $90/mo with 100,000 emails/mo and 'from $1.10 / 1,000 emails' — plus dedicated IPs at $59/IP/month, log retention of 1, 1, 5 and 30 days by tier, a one-month term with 30-day non-renewal notice, and amounts exclusive of VAT. Enterprise is request-a-quote only, the Optimize add-on's own price is not shown, the overage figures all carry the word 'from', and we found no public information on whether unused volume carries over.
Postmark
Every plan is public with its overage rate — $15.00 Basic at $1.80 per 1,000, $16.50 Pro at $1.30, $18.00 Platform at $1.20, and a free Developer plan of 100 emails a month — plus dedicated IPs at $50/month per IP with no setup fees, custom retention from $5/month, DMARC monitoring at $14/month per domain, users, domains, servers and log retention per tier, no rollover of unused email, and a 90-day refund on unused first-purchase credits. Annual plans are "Not right now", we found no public information on VAT treatment, and the captured pricing facts state the included monthly volume only for the free plan (100 emails) and, via an FAQ answer, 10,000 for the first paid tier. A buyer can get close to the real cost, but not all the way without asking.
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.