Postmark vs SES vs Mailgun for newsletters in 2026

When you self-host a newsletter, the most important decision isn't which mailing list software you run. Listmonk, Mailtrain, Mautic — they're all fine. The decision that actually determines whether your newsletter lands in inboxes is which SMTP provider you pick to relay through.

There are three real options for newsletter senders in 2026: AWS SES, Postmark, and Mailgun. Each has a specific shape, a specific cost profile, and a specific failure mode. Here's what each one actually looks like once you've committed.

AWS SES

Cheapest by a wide margin: $0.10 per thousand emails. At 50,000 emails a month that's $5. Nothing else comes close on raw cost.

That used to be the whole story. It isn't anymore.

AWS has tightened SES approval significantly in the last two years. New accounts start in a sandbox that limits you to 200 emails a day to verified addresses. Getting production access requires applying, justifying your use case, and waiting for Trust and Safety review. They reject more applications than they used to, especially for newsletter senders. The exact reasons aren't published; the rejection emails are vague boilerplate.

If you're a transactional sender — password resets, order confirmations, that kind of thing — SES is still excellent. If you're a newsletter sender, getting approved is harder than it used to be, and the approval can be revoked if your bounce rate or complaint rate drifts above their thresholds.

If you already have a production SES account from before they tightened up, keep it. It's the best deal on the market. If you're applying fresh today, plan for the possibility of being rejected and have a backup.

Postmark

Twelve times more expensive than SES: about $1.20 per thousand emails. Same 50,000 emails a month costs $60. The price difference is real and not negligible at scale.

What you get for it: easier approval, much better deliverability documentation, an actually-good dashboard with per-message tracking, EU sending infrastructure, and a support team that responds to email in hours rather than days.

Postmark also takes newsletter senders seriously in a way SES doesn't. They publish a "sending on behalf of customers" guide specifically for SaaS that relays customer emails. Their approval process is more focused on "are you doing this responsibly" than "are you the right shape of business."

The reputation infrastructure is the thing you're actually paying for. Postmark monitors bounces and complaints in real time, suspends sending if your rates drift above safe thresholds, and gives you a clear remediation path. SES has similar mechanisms but they're harder to read and less proactive.

Pick Postmark if deliverability is the actual product and the cost is acceptable. For most newsletter senders below 100,000 emails a month, the price difference vs. SES is small in absolute terms.

Mailgun

In between SES and Postmark on price and on positioning. Pricing is volume-based with a tiered structure that gets cheaper at scale; at 50,000 emails a month you're looking at $35 on their Foundation plan, with discounts for higher volumes.

Mailgun has real EU infrastructure (separate Mailgun EU domain) which matters if you have GDPR-sensitive customers. Their API is mature and the documentation is good.

The complaints we've seen about Mailgun in 2026 are mostly about deliverability inconsistency at the lower tiers and harder-to-reach support compared to Postmark. Neither is a deal-breaker, but if you're paying for the convenience of a managed SMTP relay, the consistency matters.

It's the right pick if you need EU sending, want a more flexible API than SES gives you, and don't want to pay Postmark prices.

The decision

For most self-hosted newsletter setups:

• Under 10,000 emails a month, all three are cheap. Pick on deliverability, which means Postmark.
• 10,000 to 50,000 emails a month, cost starts to matter. Postmark is around $60, Mailgun around $35, SES $5 if you can get approved.
• Above 50,000 a month, the cost gap widens significantly. If you can get SES production access and your sending is clean, the savings are real.

The other dimensions that should affect your choice:

EU customers. Mailgun EU is the simplest answer. Postmark has EU infrastructure too. SES is US-hosted by default though you can pick a region.

Time to first send. Postmark approves in 24 hours typically, sometimes faster. Mailgun is similar. SES production access can take a week and might get rejected.

What your content looks like. A clean transactional account is easy to get approved anywhere. A newsletter that's going to get spam complaints is going to struggle on SES specifically. The other two are more forgiving but only up to a point.

What we picked

Yellaro runs on Postmark. We tried SES first — got rejected twice over six weeks despite providing detailed documentation of our infrastructure, double opt-in defaults, suppression flow, and rate limits. The rejection emails were boilerplate "security reasons" with no specifics. After the second rejection we pivoted to Postmark and were approved within a day.

We pay more per email than we would on SES. The trade is worth it: a single phone call to fix a deliverability issue costs less than a week of debugging the same issue with AWS, and Postmark's EU sending infrastructure means we don't have to explain to European customers why their emails route through Virginia.

If you're starting fresh today, start with Postmark. If you grow into a volume where SES economics matter and you can get approved, that's a future migration. Don't optimize for a cost that doesn't apply yet.