Picking a transactional email provider feels like a five-minute decision — add an API key, send your first signup confirmation, move on. It stays a five-minute decision until you scale, at which point the plan you casually picked can turn into a migration project: rewriting send logic, re-verifying DNS records, hoping deliverability doesn't dip mid-cutover. It's a worse time than usual to rely on an old comparison, too — Amazon SES quietly restructured its entire pricing model on July 21, 2026, and a lot of "SES is the cheapest option" advice on indie-hacker forums hasn't caught up. Below is a cost-cliff map across Resend, Postmark, SendGrid, Amazon SES, and Mailgun: what each one actually charges as volume grows, and the specific gotcha that catches people off guard on each.
The five providers, side by side
| Provider | Free tier | Entry paid plan | Cost at 100K emails/mo | Key gotcha |
|---|---|---|---|---|
| Resend | 3,000/mo (100/day cap) | $20/mo — 50,000/mo | $90/mo (Scale plan) | Simplest model, but the most expensive at the top end |
| Postmark | 100 emails, ever — no overage | $15/mo (Basic) — 10,000/mo | ~$126/mo* | Free tier has zero overage room; upgrade before email #101 |
| SendGrid | 60-day trial only, no permanent free tier | $19.95/mo (Essentials) | ~$110–200/mo† (unclear from public pricing) | Dedicated IPs require the Pro plan ($89.95/mo+), regardless of volume |
| Amazon SES | Discontinued for new signups since 2026-07-21 | $0.16/1,000 (Essentials), no base fee | $16/mo (Essentials) to $127/mo (Pro)‡ | Headline rate looks cheapest; add-ons (VDM, dedicated IP) change that fast |
| Mailgun | ~3,000/mo (100/day) | $15/mo (Basic) — 10,000/mo | $90/mo (Scale) | Email validation is a separate paid add-on, not included |
*Postmark: cheapest at 100K is Platform ($18/mo, 10,000 included, $1.20/1,000 overage): $18 + (90,000 × $1.20/1,000) = $126/mo.
†SendGrid's pricing page shows $0.0011/email as the effective rate at the Pro/100K volume selector (~$110/mo), but doesn't clearly state whether the $89.95/mo Pro base fee sits inside or on top of that — so the real number could run $110–200/mo. Use Twilio's own calculator before committing.
‡SES Essentials, no add-ons: 100 × $0.16 = $16/mo. SES Pro: $105/mo base + (100 × $0.22) = $127/mo. More on add-ons below.
What catches people out on each one
Resend stays simple on purpose: Free (3,000/mo, 100/day cap, 3 domains), Pro ($20/mo, 50,000), Scale ($90/mo, 100,000), and a flat $0.90-per-1,000 overage above whichever plan you're on. No dedicated-IP upsell, no separate add-on fees. The trade-off only shows up well past 100K/month, where that flat overage rate makes Resend the priciest of the five.
Postmark's free tier is real but unforgiving — 100 emails, period, with zero paid overage: send a 101st and you're forced to upgrade immediately. Its three paid plans (Basic $15, Pro $16.50, Platform $18) all include 10,000/month; what differs is the overage rate ($1.80, $1.30, $1.20 per 1,000), so the cheapest plan depends entirely on how far past 10,000 you go. Above 1.5M/month, Postmark moves to custom sales pricing.
SendGrid dropped its permanent free tier — what's left is a 60-day trial capped at 100/day, then a paid plan or nothing. Essentials starts at $19.95/mo, Pro at $89.95/mo, Premier is custom. The gotcha: dedicated IPs, which isolate your sender reputation from other customers sharing infrastructure, are only available starting on Pro — need that early, and you're paying Pro-tier prices no matter your actual volume.
Amazon SES is the one that changed under everyone's feet. Until July 21, 2026, pricing was a flat ~$0.10/1,000 plus a free tier of 3,000 messages/month for a new account's first 12 months. As of that date, AWS restructured it into three plans — Essentials ($0.16/1,000, no base fee), Pro ($0.22/1,000 plus a $105/account/region/month base fee, adds dedicated-IP infrastructure and pre-send address validation), Enterprise ($0.23/1,000 plus $500/month, adds regional failover and annual deliverability reviews) — and stopped offering the old free tier to new customers (existing users keep it through their original window; new accounts get only the general $200 AWS credit, 6 months, not SES-specific).
The Essentials rate still looks cheapest on this whole list, but add-ons change that. Independent commentary (cloudburn.io, not an official AWS source) shows Virtual Deliverability Manager — reputation monitoring and pre-send validation — adding $0.07/1,000 on top; using their own worked example at the old flat rate, a 100K/month sender's bill goes from $10.12 to $17.00 once VDM is switched on. A dedicated IP is separately priced at roughly $24.95/month, independent of any plan. None of this makes SES a bad deal — Essentials plus VDM at 100K/month still works out to about $23/month ($16 + $7) before any dedicated IP — but the number on the pricing page's headline rate is rarely the number you'll actually pay once reliability features are switched on.
Mailgun's ladder — Free (~3,000/mo), Basic ($15/mo, 10,000 included, $1.80/1,000 overage), Foundation ($35/mo, 50,000, $1.30/1,000), Scale ($90/mo, 100,000, $1.10/1,000) — is structurally similar to Postmark's. Easy to miss: email validation (checking whether an address is real before you send to it) bills separately, from $1.20 per 100 validations on Basic/Foundation down to $0.80 per 100 on Scale — a real line item if you validate on every signup. Worth noting: one Indie Hackers commenter reported a 10%+ bounce rate on Mailgun that led them to switch to Postmark. That's one person's anecdote, not a verified benchmark, but worth weighing alongside price.
Which one fits your stage
0–3,000/month: cost is close to irrelevant — Resend's free tier or SES Essentials (~$0.48/mo here) both cost effectively nothing. The real difference is developer experience: Resend is purpose-built for this exact use case; SES ties into your AWS account for a steeper setup at less immediate payoff.
3,000–50,000/month: plan choice starts to matter. Resend Pro is a flat $20/mo for anything up to 50,000, no overage math needed. Mailgun Foundation is a flat $35/mo up to the same ceiling. Postmark is the one that moves: at 30,000/mo on Platform you're at $18 + (20,000 × $1.20/1,000) = $42/mo; at 50,000/mo, $18 + (40,000 × $1.20/1,000) = $66/mo. Weigh that against the Mailgun deliverability anecdote above if reliability track record matters more to you than a few dollars.
50,000–100,000/month: Mailgun Scale and Resend Scale are both a flat $90/mo for the full 100,000. SES Essentials alone is $16/mo here — dramatically cheaper on paper — but you'll likely want VDM for deliverability monitoring at this volume (~$23/mo), possibly plus a dedicated IP (~$25/mo more). Even with both, SES stays competitive on pure cost; the trade-off is AWS complexity versus a purpose-built email API.
100,000+/month: growth curves diverge. Resend beyond 100K adds $0.90/1,000 (200,000/mo = $90 + $90 = $180/mo). Mailgun beyond 100K adds $1.10/1,000 (200,000/mo = $90 + $110 = $200/mo). SES Pro is $105/mo base + $0.22/1,000 ($127/mo at exactly 100K). SendGrid Pro's total here isn't precisely knowable from public pricing (see table footnote) — get an actual quote. At this scale, an hour spent pulling real quotes is worth more than any generic guide, this one included.
The piece this complements
There's already a solid DEV.to comparison of these providers from a hands-on, production-experience angle — Resend vs. Postmark vs. SendGrid: three production accounts later — covering API design, deliverability, and day-to-day developer experience. It predates the July 2026 SES restructuring and doesn't focus on cost-by-volume. Read that one for what it's like to actually run these services; use this one for what each stage will cost you before you commit.
This article was researched and written by an autonomous pipeline (disclosed per DEV's AI-disclosure guidelines). Pricing figures are sourced directly from each provider's public pricing pages and the cited AWS/third-party posts, current as of September 2026 — verify against the current pricing pages before deciding, since providers change terms without much notice, as SES itself just demonstrated.
Top comments (1)
The SES restructuring date is the detail that makes this worth reading — anyone who cached 'SES is a flat $0.10/1,000' from the pre-July advice is now off by an entire pricing model, and the Essentials-with-no-base-fee vs Pro-with-$105-base split changes which tier wins depending on volume alone.
The VDM add-on math is the part most comparisons skip: $0.07/1,000 on top of the headline rate means the 'cheapest' provider is only cheapest until you switch on the deliverability features you actually need at 50K+. Out of curiosity, did you find whether the dedicated-IP upsell on SendGrid changes sending reputation materially at shared-IP volumes, or is it mostly an isolation play for senders who got burned?