Postmark vs Mailgun: Which Transactional Email API Should You Use?

A factual comparison of Postmark and Mailgun for sending transactional and marketing email, covering pricing, deliverability tools, and migration steps.

Updated 2026-09 · 2026

Postmark

Fast, reliable transactional email with a focus on deliverability

15month (10,000 emails)

Strengths

+Strong deliverability reputation and dedicated IP options
+Clean, readable email templates and message activity log
+Fast, well-documented API and official libraries for major languages

Weaknesses

-No true bulk marketing email support (transactional-focused)
-Free tier is a 100-email trial, not a permanent free plan
-Pricier per-email at high volume compared to Mailgun's bulk tiers

Best for

Developers who need reliable transactional email (receipts, password resets, notifications) with strong deliverability out of the box

Mailgun

Developer-friendly email API for transactional and bulk sending

35month (Foundation, 50,000 emails)

Strengths

+Handles both transactional and higher-volume bulk email
+Built-in email validation API to reduce bounces
+Flexible pay-as-you-go pricing option for variable volume

Weaknesses

-Deliverability reputation has been more inconsistent than Postmark's historically
-Free trial is time-limited (3 months) rather than a permanent free tier
-UI and docs feel less polished than Postmark's

Best for

Teams that need both transactional email and occasional bulk/marketing sends, or want inbound email parsing

Feature Comparison

Feature	Postmark	Mailgun
Free tier	100 emails/month (trial only)	100 emails/day for 3 months (trial)
Entry paid plan	$15/mo for 10,000 emails	$35/mo for 50,000 emails
Pay-as-you-go option	No	Yes
Dedicated IPs	Yes (add-on)	Yes (higher plans)
Email validation API	No	Yes
Inbound email parsing	Limited	Yes
Template editor	Yes, with layout support	Yes, basic
Message activity/log retention	45 days (higher on paid plans)	Up to 30 days depending on plan
Bulk/marketing sending	Not designed for this	Supported
API/SDK quality	Excellent, well-documented	Good, less polished docs
Deliverability reputation	Strong, dedicated focus	Good, more variable historically

The Verdict

Postmark is the better choice if your primary need is rock-solid transactional email deliverability and you don't mind paying a bit more per email. Mailgun makes more sense if you need one API to handle both transactional and higher-volume bulk sends, or want inbound email parsing. Teams purely focused on receipts, resets, and notifications tend to stick with Postmark; teams scaling into marketing or app-driven email workflows often pick Mailgun.

How to switch from Postmark to Mailgun

1Export your Postmark message activity log and suppression/bounce list as CSV from each server's dashboard before making changes.
2Manually recreate any Postmark templates in Mailgun's template editor or via the Mailgun Templates API, since there's no automated template import.
3Verify your sending domain in Mailgun and update SPF, DKIM, and DMARC DNS records — Postmark's verification doesn't transfer.
4Update your application code to use Mailgun's API endpoints and SDK, and rewrite any webhook handlers to match Mailgun's event payload format.
5Send a batch of test transactional emails through Mailgun (password resets, receipts) in a staging environment before cutting over production traffic.
6Once verified, switch your production API keys/environment variables to Mailgun and monitor deliverability and bounce rates closely for the first 1-2 weeks.

Postmark vs Mailgun: common questions

How do I export my data from Postmark before switching to Mailgun?+

Postmark lets you export your message activity log and suppression list as CSV files from the Activity and Suppressions pages in each server dashboard. Templates need to be copied manually since there's no bulk template export — you'll need to recreate them in Mailgun's template editor or via API. Sender/domain verification records (SPF/DKIM) are not exportable and must be reconfigured in Mailgun.

What features do I lose moving from Postmark to Mailgun?+

You'll lose Postmark's separated transactional/broadcast message streams, which keep your sending reputation isolated by email type. You also lose Postmark's cleaner template editor and its generally stronger out-of-the-box deliverability reputation. Mailgun compensates with email validation and inbound routing, but these aren't direct replacements.

Is Mailgun's free trial enough for a small team?+

Mailgun's trial gives 100 emails/day for 3 months, which covers light transactional volume for testing but won't work long-term for even a small production app. Most small teams will need the Foundation plan at $35/month for 50,000 emails once the trial ends. Check current limits on mailgun.com/pricing since trial terms have changed before.

Does Mailgun integrate with the same tools Postmark does?+

Both integrate with common frameworks (Rails, Django, Laravel, Node) and have official SDKs, so most app-level integrations transfer with minimal code changes. If you use Zapier or a CMS plugin tied specifically to Postmark, you'll need to swap it for the Mailgun equivalent. Webhook payload formats differ, so any code parsing Postmark webhooks needs to be rewritten for Mailgun's webhook schema.

Will switching to Mailgun cost more or less over time?+

At low volume (under 10,000 emails/month), Postmark is often cheaper or comparable. At higher volume (50,000+ emails/month), Mailgun's Foundation and Scale plans can be more cost-effective per email, especially with pay-as-you-go pricing for variable send volumes. Run your actual monthly email count through both pricing pages before deciding — the crossover point depends on your volume and plan tier.