Cheapest Transactional Email API: Price per 100,000 Emails Compared
Fifteen transactional email APIs priced at 100,000 emails a month, per 1,000 and over 12 months, plus the costs that do not appear on the price line.
Direct answer. Among transactional email APIs that include a message log and dashboard, the cheapest at 100,000 emails a month is AgentiSend: $28 on monthly billing, $16.80 a month on yearly billing, or $199 once for 1.5 million emails used at up to 100,000 a month. Amazon SES is cheaper per message at $10 for the same 100,000 on à la carte pricing, and it is the right choice if you will build logging, retries and reporting yourself.
How we put this together
Our source for every figure here is the provider's own pricing page. We read the pages of AgentiSend, Resend, Amazon SES, Postmark, Mailgun, SendGrid, MailerSend, Mailtrap, SMTP2GO, Brevo, Loops, Plunk, Mailjet, AgentMail and Cloudflare Email Service on 9 November 2026, then went through their documentation between 28 September and 10 November 2026. We did not run send tests; each price is the cheapest published plan that holds the volume, and the per-1,000 and 12-month figures are our arithmetic from those prices.
What 100,000 emails a month costs
| Provider | Cheapest plan that holds 100,000 | Per month | Per 1,000 | 12 months |
|---|---|---|---|---|
| AgentiSend (our pick, yearly) | Pro 100,000, billed yearly | $16.80 | $0.17 | $201.60 |
| AgentiSend (monthly) | Pro 100,000 | $28 | $0.28 | $336 |
| Amazon SES (à la carte) | Pay per message | $10 | $0.10 | $120 |
| Amazon SES (Essentials) | Pay per message, new accounts | $16 | $0.16 | $192 |
| Mailtrap | Basic 100,000 | $30 | $0.30 | $360 |
| SendGrid | Essentials 100,000 | $34.95 | $0.35 | $419.40 |
| Resend | Pro 100,000 | $35 | $0.35 | $420 |
| Cloudflare Email Service | Workers Paid, metered | $38.95 | $0.39 | $467.40 |
| Loops | Growth, up to 5,000 contacts | $49 | Priced by contact | $588 |
| MailerSend | Starter 100,000 | $68 | $0.68 | $816 |
| Mailgun | Foundation 100,000 | $75 | $0.75 | $900 |
| SMTP2GO | 100,000 plan | $75 | $0.75 | $900 ($750 billed yearly) |
| Brevo | Starter 100,000 | $82 | $0.82 | $984 |
| Plunk | Pay as you grow | $100 | $1.00 | $1,200 |
| Mailjet | Premium 100,000 | $112 | $1.12 | $1,344 ($1,209.60 yearly) |
| Postmark | Basic 125,000 | $115 | $1.15 for 100,000 sent | $1,380 |
| AgentMail | Startup | $200 | $2.00 | $2,400 |
Postmark has no 100,000 step, so you pay for 125,000. Loops does not meter emails on paid plans, so its price depends on how many subscribed contacts you have, not on how much you send. AgentMail's Startup plan is sized around inboxes (150 of them), which is a different product.
Three ways to pay AgentiSend for 100,000 a month
AgentiSend is the one provider here that sells the same volume three ways, and the cheapest depends on how long you will stay.
| Billing | What you pay | Effective per month at 100,000 | Per 1,000 |
|---|---|---|---|
| Monthly | $28 a month | $28 | $0.28 |
| Yearly (40% off) | $201.60 a year | $16.80 | $0.17 |
| Lifetime $199 | Once, for 1.5 million emails at up to 100,000 a month | $13.27 over 15 months | $0.13 |
| Lifetime $349 | Once, for 3 million emails at up to 100,000 a month | $11.63 over 30 months | $0.12 |
The lifetime figures assume you send the full 100,000 every month until the emails run out. Lifetime emails do not expire, so a slower month stretches the plan rather than wasting it. A lifetime plan is refunded in full only if no email has been sent on it.
Against Resend, the comparison most teams run, yearly billing at 100,000 a month is 52% below Resend's $35 monthly price, since Resend sells no yearly plan. The smallest lifetime plan shows the widest gap: $49 buys 250,000 emails at up to 25,000 a month, which is 10 months of sending. Ten months of Resend's $20 Pro plan is $200, so the lifetime plan costs 75% less.
The costs that are not on the price line
The cheapest invoice is not always the cheapest way to get mail delivered. Four line items change the real total.
Message history. When a customer says their receipt never arrived, someone has to look it up. SES's pricing page includes no message log at all; you configure and pay for storage such as S3 and CloudWatch yourself. Mailgun keeps 5 days of logs on Foundation, SendGrid 3 days on Essentials, Mailtrap 5 days on Basic. AgentiSend's Pro plan, the one priced above, keeps 90 days.
Duplicates. A send API without idempotency keys bills you twice for every retried timeout and sends the customer two copies. Two copies of a receipt are a reliable source of spam complaints, and complaints are what get domains paused. The SES SendEmail reference and SendGrid's mail-send reference document no idempotency key; Postmark says to detect duplicates yourself. AgentiSend remembers a key for 7 days, Resend for 24 hours.
Overage. Go over your plan and the rate changes. Resend charges $0.90 per 1,000 on Pro, Postmark $1.80 per 1,000 above Basic's inclusion, MailerSend $1.30. AgentiSend charges $0.72 on Pro and $0.60 on Scale, but overage is off by default: sending pauses at the inclusion with plan_limit_reached unless the owner turns it on and sets a ceiling. A sign-up form flooded by bots then costs you a pause, not a bill.
A dedicated IP. Few senders at 100,000 a month need one. If you do, SES charges $24.95 a month per IP, Resend $30 on Scale, Postmark from $50 at 300,000 a month, and Mailgun includes one on its $90 Scale plan. AgentiSend offers one on request on Scale.
The cheapest options, one by one
1. AgentiSend: cheapest with a log, a dashboard and duplicate protection
Best for: teams who want a hosted API with 90 days of history and a price near SES's.
At $16.80 a month on yearly billing, 100,000 emails cost 80 cents a month more than SES Essentials and include what SES leaves to you: a searchable log, signed webhooks with replay, automatic suppression of hard bounces and complaints, 2048-bit DKIM, and refusals that carry a fix naming the next call. The free plan (5,000 a month, 170 a day) and the $9 Starter plan (30,000) cover the volumes below this comparison. A recipient counts as one email, so a message to two people on To and one on CC is three.
Plans and the full volume ladder are at agentisend.com, and the price-by-price comparison with Resend is on the AgentiSend vs Resend page.
2. Amazon SES: cheapest per message
Best for: AWS-native teams sending high volume with engineers to build the missing pieces.
$0.10 per 1,000 on à la carte, $0.16 on Essentials for new accounts from 21 July 2026, and up to $200 in credits for new AWS accounts.
Watch out for: new accounts start in a per-Region sandbox (verified recipients only, 200 messages per 24 hours, 1 per second). AWS Support's initial response to a production-access request comes within 96 hours, and can take longer if it needs more information.
3. Mailtrap
Best for: teams who want a low price with SOC 2 Type II listed on every plan.
Watch out for: 5 days of logs on Basic, and no documented idempotency key.
4. SendGrid
Best for: teams who may need marketing features from the same vendor later.
Watch out for: 3 days of activity on Essentials; the dedicated IP starts on Pro at $89.95.
5. Resend
Best for: teams who prefer an audited provider at a modest premium.
Watch out for: monthly billing only, and $0.90 per 1,000 overage on Pro.
6. Cloudflare Email Service
Best for: apps already on Cloudflare Workers that send at high volume.
Watch out for: the limits page says new accounts start with a quota that rises with sending behaviour, without publishing the starting number, and no idempotency key is documented on the REST send page.
Above 100,000: where the order changes
| Emails a month | AgentiSend monthly | AgentiSend yearly | SES à la carte | Cloudflare | SMTP2GO | Resend | Mailgun |
|---|---|---|---|---|---|---|---|
| 250,000 | $136 | Not quoted | $25 | $91.45 | $170 | $170 | $215 |
| 500,000 | $280 | $168 | $50 | $178.95 | $280 | $350 | $400 |
| 1,000,000 | $520 | $312 | $100 | $353.95 | $520 | $650 | $700 |
At 250,000, AgentiSend's figure is Pro 100,000 plus overage at $0.72 per 1,000, which the owner switches on with a ceiling, so a spike never becomes a surprise bill. On yearly billing AgentiSend is $168 at 500,000 and $312 at 1 million, below every hosted provider in the table.
Questions people ask
What is the cheapest email API per 100,000 emails? Amazon SES at $10 on à la carte pricing. Among APIs that include a message log, AgentiSend at $16.80 a month billed yearly, or $28 billed monthly.
Does a cheaper email API mean worse deliverability? Not by itself. Placement follows your domain's authentication, list quality and complaint rate. What a cheaper API can lack is the tooling that protects those: suppression, idempotency and logs long enough to investigate.
Is the lifetime plan worth it? If you will send steadily for more than a year, the $199 plan works out to $0.13 per 1,000 at 100,000 a month, below SES Essentials ($0.16) and above only SES à la carte ($0.10). If your volume is uncertain, monthly billing keeps you flexible.
Are sends to suppressed or simulator addresses billed? Sends to simulator.agentisend.com cost nothing. For other providers, check their pages; we did not find this stated.
Sources
Pricing pages read 9 November 2026: aws.amazon.com/ses/pricing, docs.mailtrap.io (billing plans), twilio.com/en-us/products/email-api/pricing, resend.com/pricing, developers.cloudflare.com/email-service/platform/pricing, loops.so/pricing, mailersend.com/pricing, mailgun.com/pricing, smtp2go.com/pricing, brevo.com/pricing, docs.useplunk.com/concepts/billing, mailjet.com/pricing, postmarkapp.com/pricing, agentmail.to/pricing. Documentation read 28 September to 10 November 2026: docs.aws.amazon.com/ses/latest/dg/request-production-access.html, docs.aws.amazon.com/ses/latest/APIReference-V2/API_SendEmail.html, twilio.com/docs/sendgrid/api-reference/mail-send/mail-send, postmarkapp.com/support/article/what-is-an-idempotency-key, resend.com/docs/dashboard/emails/idempotency-keys, developers.cloudflare.com/email-service/platform/limits.