Mailgun vs Postmark

Reachkit makes a cold email tool, so it doesn’t compete with either of these for app email. I checked every price on this page in October 2026 against Mailgun’s and Postmark’s own pages.

Mailgun and Postmark both deliver the email your software sends, through an API or SMTP, to people who agreed to receive it. My verdict: Mailgun is the cheaper toolkit across the middle of the range, with paid add-ons around it. Postmark is the narrower service, with long history and app mail kept apart from bulk mail by default.

Pick Mailgun if:

• You send roughly 21,000 to 280,000 emails a month. 50,000 cost $35 on Foundation against $55 on Postmark Basic.
• You want your own IP address below 300,000 emails a month. Foundation 100k includes one for $75.
• You’d like a bigger free plan (100 emails a day), or validation and placement tests from the same vendor.

Pick Postmark if:

• You trace delivery problems in the logs and want 45 days of history on every plan, where Mailgun Basic keeps one day.
• You want receipts and newsletters on separate streams and IP ranges as the default, not as a project.
• A few teammates need logins at 10,000 emails: Postmark Basic allows 4 users for $15, while Mailgun’s multi-user access starts at $35.

Checked October 2026. Prices in USD, billed monthly, from each vendor’s own pages.

Both let you start free without a card, and Postmark adds a human review before your first email to anyone outside your own domains.

Mailgun: the free plan sends 100 emails a day from one custom domain, with one user and one day of logs. Foundation and Scale start with a free month. You verify your domain through DNS (SPF, DKIM, DMARC and BIMI on every plan), then use the HTTP API or SMTP relay; Mailgun’s FAQ recommends the API for applications. One account can send from US or EU data centers.

Postmark: its free Developer plan covers 100 emails a month and never expires. You add DKIM and Return-Path records, and someone at Postmark reviews the account. Before approval you can only email addresses on domains you’ve verified, and link tracking is disabled. Postmark says most reviews are done in under 24 hours on weekdays. On Trustpilot, one reviewer in June 2025 described waiting a week, and another in September 2025 a refusal with no reason given.

Both date from 2010; Sinch has owned Mailgun since 2021, ActiveCampaign Postmark since 2022. If a launch depends on email, I’d open either account a week early and send real traffic before the date: Postmark has its review, and Mailgun’s policy lets it judge violations at its sole discretion and suspend the account.

Postmark protects app mail by keeping it apart from bulk mail, and Mailgun by putting a dedicated IP within reach at 100,000 emails a month.

Postmark runs transactional mail and broadcasts on separate message streams and says the two never share IP ranges. Most customers stay on its shared pools: a dedicated IP is a $50 monthly add-on for Pro or Platform customers who send at least 300,000 emails a month, and Postmark argues that for most senders a well-kept shared pool works better. Its homepage also says it vets “every new sender carefully”.

Mailgun sends lower plans from shared IPs it assigns dynamically. One dedicated IP is included from Foundation 100k and on every Scale tier, and extras cost $59 a month. Scale adds IP pools, which is how you’d keep newsletters off the address your receipts use. Mailgun’s help center suggests a dedicated IP once you consistently send 100,000 a month, and a July 2025 release added control of IP warm-up through the API.

Both write limits into their rules. Mailgun’s acceptable use policy caps bounces at 5%, unsubscribes at 1.4% and spam complaints at 0.08%. Postmark’s terms set complaints under 0.1% and bounces under 10%.

To test placement, Mailgun sells Optimize: 25 inbox placement tests and 2,500 validations for $49 a month. Postmark’s own Mailgun migration guide lists placement tests and email validation among the Mailgun features Postmark doesn’t offer.

Postmark keeps far more history on its cheapest plans, and Mailgun opens up seats and domains once you pay for Foundation.

• History. Mailgun keeps logs for 1 day on Free and Basic, 5 on Foundation and 30 on Scale. Postmark keeps 45 days of activity on every plan, Free included, adjustable from 7 to 365 days from $5 a month on Pro and up.
• Seats and domains. Mailgun’s Free and Basic plans are limited to one sending domain, and its FAQ excludes both from the unlimited-users offer. From Foundation, users are unlimited and one account holds 1,000 domains. Postmark Basic allows 4 users and 5 domains, Pro 6 and 10, and Platform removes the caps from $18 at 10,000 emails.
• Inbound mail. Mailgun’s routes forward an incoming message or post it to your app: one route on Free, five on Basic, full routing from Foundation. Postmark turns inbound mail into JSON for your webhook, on Pro and Platform only. Neither gives you an inbox to read replies in.
• Bounces. Postmark deactivates an address after a hard bounce or spam complaint. Mailgun classifies bounces, manages suppressions and can alert you when bounce rates climb.
• Support. Mailgun answers tickets below Scale; live phone and chat start at $90. Postmark’s pricing page doesn’t list support by plan, but its Mailgun comparison page offers email, chat in business hours and phone, and says “You’ll usually hear back in a couple of hours.”

Neither Mailgun nor Postmark writes email copy with AI, but both publish official MCP servers, with different guardrails.

MCP is the protocol that lets an assistant such as Claude call another service’s tools, for example to look up a password reset that never arrived.

• Mailgun’s server is open source (Apache 2.0) and runs on your own machine, with no hosted version. It exposes 50+ operations, from sending to domains, templates and routes, and leaves out every delete operation. Its 15 Skills joined the Cursor Marketplace in August 2026.
• Postmark’s server (MIT licence) also runs locally. Version 2.0, from July 2026, has 24 tools, including a delivery diagnosis tool, labelled read-only or destructive. It can send email and delete templates, webhooks and suppressions, so its README warns against auto-approving those tools in untrusted environments.

Mailgun’s one AI feature in the product is send time optimization on Scale, which times each email from that recipient’s engagement. Mailgun also adds role-based API keys from Foundation and SAML SSO on Scale; Postmark takes 500 messages per batch call.

One caution: in September 2025 an unofficial npm package named postmark-mcp copied every email it sent to an attacker. Postmark had nothing to do with it; the official package is @activecampaign/postmark-mcp.

Mailgun sells sending as one product among paid add-ons, while Postmark puts everything it does into one account with three plans.

Around Mailgun Send sit Optimize ($49 a month, or $99 adding spam trap and blocklist monitoring plus Google Postmaster Tools and Microsoft SNDS data), Validate (from $1.20 per 100 addresses, 5,000 included on Scale) and Inspect (client previews for $99 or $199 a month). Postmark’s extras are dedicated IPs, longer history and DMARC reports at $14 or more per domain each month, and newsletters to opted-in lists go out on a Broadcast stream in the same account at no extra fee.

Each vendor publishes a page about the other, and both read as sales pages:

• Mailgun’s page (published November 2025) gives Trustpilot scores of 4.1 and 2.0, which still held in October 2026. But it lists Mailgun’s event retention as “30 days on all paid tiers”, against 1 day on Basic and 5 on Foundation on its pricing page, and prices 100,000 emails at $90 rather than the $75 Foundation 100k tier.
• Postmark’s page concedes that address validation, A/B testing and scheduled delivery are Mailgun-only. It also credits Mailgun’s paid accounts with 30 days of events, and its price table shows overage rates down to $0.60 per 1,000, below the $1.15 to $1.80 on Postmark’s pricing page.

Mailgun costs less from about 21,000 to about 280,000 emails a month. Above that, the cheaper one changes from tier to tier, and Mailgun’s price there includes a dedicated IP.

Assumptions: October 2026 list prices from each vendor’s public pricing page, billed monthly, no tax or add-ons, cheapest tier or tier plus overage. Below about 21,000 emails both Basic plans charge $1.80 per 1,000 extra, so they cost the same.

• Postmark’s two overage rates. At the $0.80 per 1,000 its Mailgun comparison page lists for the 700,000 tier, 1 million emails would cost $695, just under Mailgun’s $700.
• A second dedicated IP costs $59 a month at Mailgun and $50 at Postmark.
• Billing. Mailgun’s Send page shows no annual plan, and Postmark’s FAQ answers the yearly question with “Not right now, but we’d like to!” Both bill overage on the next invoice. Postmark’s unused emails don’t roll over.

Mailgun rates just above 4 on G2, Capterra and Trustpilot, while Postmark rates higher on G2 and Capterra and much lower on Trustpilot. As of October 2026:

Postmark’s samples are small, with 10 Trustpilot reviews in the past year, so a handful of reviewers moves its averages.

Mailgun: G2’s review summary credits reliable delivery and an easy integration, and reviewers point to the detailed logs. The criticism is about accounts and help: several Capterra reviewers, some long-time customers, describe accounts disabled with no warning, one reviewer, in September 2025, blaming “a flawed automated system” and calling support “extremely slow”.

Postmark: the praise is for setup, scored 9.2 to 9.3 on G2 compare pages, and for delivery; a five-star Trustpilot review from February 2026 reports every email landing in the inbox within three days. The low scores return to three themes in 2025 and 2026: support (“slow and unresponsive”, October 2026), approval waits, and whole accounts blocked with transactional mail included, in one January 2026 case after a single B2B broadcast. Five Trustpilot reviewers date a decline to the ActiveCampaign sale.

This is our product, and it only fits readers who came here for outreach: Reachkit isn’t built to send password resets or receipts. If you were weighing Mailgun or Postmark to email people who never signed up, both rule it out. Mailgun’s policy bans bought, rented or scraped lists, and Postmark’s terms allow only permission-based ones.

Reachkit sends cold email from Google or Microsoft inboxes you connect, with no per-inbox fee. Or it registers new lookalike domains at $15 a year, creates inboxes on them at $5 a month each and switches on AI-written warmup automatically. Growth costs $39 a month after a 30-day trial with no card (October 2026). Your app’s mail stays on whichever API you pick; Reachkit vs Instantly shows how it compares with another cold email sender.

Moving between Mailgun and Postmark keeps your domain and your suppression lists and rebuilds most of the rest. Postmark’s Mailgun migration guide maps the pieces:

• Domain: verify it again on the new side, with DKIM and Return-Path records on Postmark or SPF and DKIM on Mailgun.
• Suppressions: export bounces, complaints and unsubscribes first. They map to Postmark’s Suppressions API.
• Tags and metadata: Mailgun’s o:tag becomes Tag, and v: variables become Metadata.
• Gone on Postmark: scheduled delivery, raw MIME sends, mailing lists and route rules. Inbound mail arrives at your webhook as JSON instead.
• Limits: Postmark’s SMTP doesn’t support port 465, and a message tops out at 10 MB and 50 recipients.
• Left behind: dedicated IPs, logs and API keys. Export the logs you need first (Mailgun keeps 1 to 5 days below Scale); Mailgun settles any balance before closing an account.

The guide’s metadata dates it to 2017, so check field names against current docs. Get a new Postmark account approved before moving traffic, budget for Mailgun Foundation if you send from several domains, and move one kind of message at a time.

If I were choosing for an app, I’d decide on three things: monthly volume, how far back I need logs, and whether I want my own IP. For a small product where support tickets start with “did the reset email arrive?”, Postmark’s 45 days of history and separate streams are worth the same $15. From about 21,000 to a few hundred thousand emails a month, Mailgun is cheaper, and Foundation 100k comes with an IP for $75. Past that, I’d price my exact volume on both pricing pages, because the lead keeps switching. Whichever I picked, I’d keep bounces low, since both can shut an account down.

Related: the Mailgun profile, the Postmark profile, Mailgun alternatives, Postmark alternatives, Mailgun vs SendGrid and SendGrid vs Postmark.