shouldiuse.io

Comparison

Postmark vs Mailgun

Postmark lands on Worth it, and Mailgun lands on Depends.

Postmark versus Mailgun
ComparePostmarkMailgun
VerdictWorth itDepends
Best forDeveloper teams sending app emailDev teams sending app email
Who it's not forMarketers wanting drag-and-drop newslettersNon-technical marketers wanting drag-and-drop campaigns
PrivacyNo known public vulnerabilities found in the sources reviewed.²No breaches found in reviewed sources; vendor runs a public security portal and published a Log4j mitigation response.16
Support qualityNo support evidence in sourcesThird-party reviews flag suspensions and billing surprises
Public sentimentUsers consistently praise deliverability and speed, with developers citing successful migrations away from SendGrid.⁹Developers report it works fine via SMTP and API, while third-party reviews flag billing surprises and suspensions.
Biggest gotchaPostmark's *.pstmrk.it tracking domain has been flagged as malicious by some security tools . deliverability risk.10Users report pricing escalation and unpredictable overage costs as volume grows

Pick Postmark when

  • Developer teams sending app email
  • SaaS receipts, resets, notifications
  • Teams escaping SendGrid spam issues
  • Rails/Heroku production apps

When Postmark is not a fit

  • Marketers wanting drag-and-drop newsletters
  • Non-technical founders with no dev help
  • High-volume bulk senders on a budget
  • Teams wanting CRM and email in one tool

Pick Mailgun when

  • Dev teams sending app email
  • High-volume transactional senders
  • API/SMTP integration shops
  • Teams needing deliverability and validation tooling

When Mailgun is not a fit

  • Non-technical marketers wanting drag-and-drop campaigns
  • Tiny side projects . cheaper alternatives exist
  • Budget-sensitive senders who can't absorb overage surprises
  • Anyone unwilling to manage DNS and sending reputation

Sources

  1. Postmark: Fast, Reliable Email Delivery Servicepostmarkapp.com
    official
  2. Postmark Product Security Pagepostmarkapp.com
    security
  3. Postmark Review: Features, Pricing & Deliverability (2026)wpmailsmtp.com
    review
  4. Postmark Review: Features, Pricing, Pros & Consfluentsmtp.com
    review
  5. I Tested 6 Postmark Alternativesmailtrap.io
    review
  6. Postmark Review 2026: Honest Test, Pros, Cons and Pricinghackceleration.com
    review
  7. Postmark Review 2025: Is It Worth the Hype?emailsoftwareinsights.com
    review
  8. Postmark Review: Features, Pricing & Alternatives (2026)coldiq.com
    review
  9. ActiveCampaign Postmark Reviews & Product Detailsg2.com
    review
  10. *.pstmrk.it domain flaggedhelp.tempo.io
    security
  11. Postmark setup for Rails on Herokumedium.com
    official
  12. SendGrid Giving You Trouble? Use Postmark Insteadforum.bubble.io
    review
  13. Mailgun official sitemailgun.com
    official
  14. Mailgun product security pagemailgun.com
    official
  15. Mailgun SAML Authenticationmailgun.com
    official
  16. Mailgun's Active Defense Against Log4jmailgun.com
    security