Teddy Hartanto

thoughts and experiments

Which Email Provider Should You Use in 2025? Postmark vs Mailgun

Email is a core communication channel we rely on at Hozuko, Singapore’s direct-landlord property rental platform. We primarily send transactional emails, not marketing emails. This write-up evaluates email providers from that perspective.

Here are some popular options:

  1. Amazon Simple Email Service (Amazon SES)
  2. Postmark
  3. Resend
  4. SendGrid
  5. Mailgun

Initially, I assumed these services were more or less the same—so I didn’t think my choice would matter much.

  • Amazon SES: Cheap and reportedly reliable. I’ve only used it briefly. I generally avoid Amazon tools due to their clunky UI/UX.
  • Postmark: Frequently recommended on Reddit and tech blogs.
  • SendGrid: I’ve used it before at Ninja Van, but I wanted to try something different.
  • Resend: Founded in 2023. As a newer player, I was cautious—new companies often face growing pains that mature ones have already solved. That’s just a rule of thumb, of course.
  • Mailgun: I picked it because an engineer I admire uses it. I assumed it’d be a safe bet.

Oh boy, was I wrong.

I had a horrible experience with Mailgun.

TL;DR: I had serious deliverability issues with Mailgun. Support took 2–3 weeks to respond, claimed they fixed the problem (they hadn’t), and pushed me to upgrade. I upgraded—still broken. I filed another ticket and waited again. Eventually, I switched to Postmark and had a flawless experience. Here’s what happened.

Comparing Postmark to Mailgun

Email Open Tracking

Before the deliverability issues, I encountered a peculiar problem with Mailgun’s open tracking: every email was marked as “opened” just one second after delivery.

Their response:

This can happen due to antivirus software, spam filters, or email clients that auto-open messages. We recommend using tags to view unique opens.

Fair enough. I implemented a workaround to ignore instant open events.

After switching to Postmark—no such issue.

IP Reputation

Checked via SenderScore:

  • ✅ Postmark: 97
  • ❌ Mailgun: 13

Postmark separates transactional IPs from bulk email pools. Mailgun doesn’t. I was repeatedly assigned low-reputation IPs that caused Microsoft to block my emails.

When I raised this with Mailgun, their excuse was:

There will always be risks associated with shared IPs… think of it like a highway: multiple drivers share the risk of its use, but still choose to use it in order to benefit.

I can’t justify using a dedicated IP—I don’t send enough volume, nor do I have the capacity to manage it.

Meanwhile, Postmark just worked.

Email Logs

  • ✅ Postmark $15/mo plan: 45-day retention
  • ❌ Mailgun $15/mo plan: 1-day retention

UI/UX

  • ✅ Postmark: Clean, modern, and intuitive
  • ❌ Mailgun: Dated and clunky

Customer Support

  • ✅ Postmark: I haven’t needed support—because nothing has broken
  • ❌ Mailgun: Slow, vague, and ultimately unhelpful

Conclusion

I can’t speak for every email provider—but I can confidently compare the two I’ve used.

❌ Don’t use Mailgun:

  • Poor IP reputation = frequent deliverability issues (especially with Microsoft)
  • Support is slow, indirect, and upsells without resolving issues
  • Misleading communication
  • Minimal log retention
  • Outdated interface
  • Wasted weeks of my time

✅ Use Postmark:

  • Excellent deliverability
  • Great IP reputation
  • Better UI/UX
  • No issues so far—everything just works

If you’re sending transactional emails in 2025, skip the frustration.
Go straight to Postmark.