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Postmark alternative: Irisend vs Postmark
Postmark is priced per tier with an included volume and a declining per-1,000 overage; Irisend is priced the same shape. The clearest differences show up in webhook security and where the data actually lives.
Facts below are sourced from Postmark's own pricing, security and EU-privacy pages, fetched 3 November 2026. Irisend is in early access: every team sends free today (capped at 10,000 emails/month); the prices below are Irisend's listed launch pricing, not yet billed.
Information checked on ; see sources at the bottom of this page. Facts come from Postmark's own pricing and docs pages, recorded in docs/research/2026-11-03-competitor-comparison.md.
Feature by feature
| Feature | Irisend | Postmark |
|---|---|---|
| Starting price | Free today (early access, 10,000 emails/mo cap, no credit card) · listed launch price from €20/mo | Free: $0/mo, 100 emails/mo, no overage allowed. Paid from $15/mo (Basic, 10,000 emails/mo, $1.80/1,000 overage). |
| Price at 100,000 emails/mo (listed) | €35/mo listed launch price (Pro plan, 100,000 emails/mo) — not yet billed; every team sends free during early access | ≈$133.50/mo (Pro plan: $16.50/mo + 90,000 emails over the included 10,000 at $1.30/1,000)Computed from Postmark's published Pro overage rate; Postmark doesn't publish a single 100k-inclusive tier the way Irisend/Resend/Mailgun do. |
| Free tier | 3,000 emails/mo, 100/day cap, no overage, once the listed plans take effect | 100 emails/mo, no overage allowed — testing only, not a sustained free tier |
| SMTP relay | smtp.irisend.com, ports 465 (implicit TLS) / 587 (STARTTLS) | Included on every plan per Postmark's feature matrix |
| Idempotency key on send | Idempotency-Key header, 24h, checked against the request body (409 on a changed replay) | No idempotency key documented on Postmark's send or webhook pages reviewed |
| Webhook signing | Standard Webhooks / Svix-compatible HMAC (byte-compatible with existing svix verifiers) | No HMAC signing — Postmark's own docs say so directly; the recommended protection is HTTP Basic Auth plus IP allowlisting |
| Sending regions | us-east-1, eu-west-1, sa-east-1, ap-northeast-1 — selectable per domain | US-based only — Postmark's own EU-privacy FAQ states it has no servers in the EU |
| Dedicated IPs | Not offered | Not offered on any published tier per Postmark's feature matrix |
| Self-host on your own AWS | No — all sending runs on Irisend's own managed AWS SES; no bring-your-own-AWS option ships today | No bring-your-own-AWS option found on Postmark's pages |
| DMARC monitoring | Built in: pass-rate summary, source breakdown, raw aggregate reports per domain | Not found on Postmark's pricing/feature pages |
| Sub-accounts / multi-tenant | Built in: Connect sub-accounts with an embeddable React domain-verification widget | Not found on Postmark's pricing/feature pages (Message Streams separate sending pools within one account, which is a different feature) |
| SOC 2 Type II (own audit) | Not yet — publicly stated as a roadmap item, not claimed | No — Postmark's own security page states Postmark itself has not undergone a SOC audit; only its data center has |
What Irisend does that Postmark doesn't
Cryptographically signed webhooks
Every Irisend webhook carries a Standard Webhooks/Svix-compatible HMAC signature, verifiable without trusting source IPs. Postmark's own docs state it "does not currently support HMAC webhook signature verification" and recommend Basic Auth plus IP allowlisting instead.
An EU sending region
eu-west-1 is a selectable region for Irisend domains today. Postmark's EU-privacy FAQ states Postmark has no EU servers at all.
A documented idempotency contract
A 24-hour, body-hash-checked Idempotency-Key with distinct 409 responses for a changed-body replay versus a genuinely concurrent duplicate — not found anywhere in Postmark's API or pricing docs reviewed.
Where Postmark is honestly stronger
Configurable retention up to a year
Pro and Platform plans let you raise data retention to 365 days as an add-on (45-day default). Irisend's retention period isn't published on a comparable page, so no comparison is made here.
A decade-plus deliverability reputation
Postmark has built its brand specifically around transactional deliverability since 2010; Irisend is a five-week-old domain with no comparable track record to point to yet.
Production pricing, live today
Postmark's prices above are what customers actually pay right now. Irisend is still in early access (free for everyone, capped at 10,000 emails/month) — its listed prices aren't billed yet.
Verdict
Postmark's strength is a long-standing reputation and granular retention controls. If unsigned webhooks and no EU region are deal-breakers for your stack, Irisend's signed webhooks, eu-west-1 support and documented idempotency contract are where its model is built differently.
Frequently asked questions
Next
Read the full API reference, the Resend migration guide, or see pricing.
Sources (checked 3 November 2026)
Postmark is a trademark of its respective owner. Irisend is not affiliated with, endorsed by, or sponsored by Postmark. Spotted an inaccuracy? [email protected].