Best transactional email services in 2026

For receipts, resets and sign-in codes from an app, Unitpost ranks first on the balance of a clean API, a large free plan and a cheap first paid step. Postmark has the strongest public deliverability record, SendGrid, Mailgun and Amazon SES are proven at the highest volumes, and Resend has the most familiar API for newer apps.

Updated November 2, 2026. We make Unitpost, and it is on this list. Every score has a reason and the weights are published below, so you can re-rank it for your own needs. How we scored

#	Product	Best for	Free plan	Score
1	Unitpost	app teams sending both kinds of email	5,000 emails a month, 200 a day, no card	4.0
2	Postmark	mail that must reach the inbox	100 emails a month	3.7
3	Resend	developer-first transactional email	3,000 emails a month, 100 a day	3.7
4	Mailgun	high-volume senders and validation	100 emails a day on one domain	3.6
5	Brevo	marketers who want a full suite	300 emails a day	3.5
6	Amazon SES	lowest cost at very high volume	None for SES; new AWS accounts get up to $200 in credits	3.5
7	MailerSend	a cheap first paid plan	500 emails a month, card required	3.4
8	SendGrid	enterprises and multi-tenant platforms	None: a 60-day trial at 100 emails a day	3.2

What to check before you pick one

Separate transactional and marketing mail, by stream, category or subdomain, so a campaign's complaints don't slow a reset
Idempotency keys on sends, so a retried request never sends a second receipt
Webhooks for bounces and complaints, and a suppression list your code can read
SPF, DKIM and DMARC set up on your own domain before the first real send

The picks

#1 · 4.0 / 5

Unitpost

Best for app teams sending both kinds of email

Transactional and marketing email on one API, one contact list and one bill, with a permanent free plan and an importer for six providers.

Pros

Permanent free plan, no card
One-key import from SendGrid, Resend, Mailgun, Postmark, Brevo and Loops
REST API, SMTP relay, MCP server and nine SDKs on every plan
Unlimited contacts on paid plans, priced by sends

Cons

A newer sender, without a long public track record
No sub-accounts, and dedicated IPs are not launched yet
SMS is on paid plans only

Free plan: 5,000 emails a month, 200 a day, no card
Paid from: $10 a month for 20,000 emails
Priced by: Emails sent

Start free See pricing

#2 · 3.7 / 5

Postmark

Best for mail that must reach the inbox

Transactional email known for fast, reliable inbox placement, with bulk mail kept on separate broadcast streams. It costs more, and the free plan is for testing.

Pros

The best-regarded deliverability record here
Transactional and bulk mail kept on separate streams
45 days of message content and good debugging tools

Cons

The free plan is 100 emails a month
No audience or campaign tools, and no inbound on Basic

Free plan: 100 emails a month
Paid from: $15 a month for 10,000 emails
Priced by: Emails sent

Unitpost vs Postmark Visit Postmark

#3 · 3.7 / 5

Resend

Best for developer-first transactional email

A clean, modern email API from the team behind React Email, with inbound email and an official MCP server on every plan. Marketing contacts are billed on a separate plan.

Pros

A modern API with clear errors and many SDKs
Inbound email on every plan, free included
React Email for building templates in code

Cons

Marketing is a second plan, priced by contacts ($40 a month for 5,000)
Free sending is capped at 100 emails a day

Free plan: 3,000 emails a month, 100 a day
Paid from: $20 a month for 50,000 emails
Priced by: Sends and contacts

Unitpost vs Resend Visit Resend

#4 · 3.6 / 5

Mailgun

Best for high-volume senders and validation

A long-running email API with address validation and inbox placement testing. Strong at volume, with marketing campaigns left to other tools.

Pros

Email validation and inbox placement testing
EU region for data residency
Proven at very high volume

Cons

The free plan keeps logs for one day, on one domain
Marketing campaigns need another tool

Free plan: 100 emails a day on one domain
Paid from: $15 a month for 10,000 emails
Priced by: Emails sent

Unitpost vs Mailgun Visit Mailgun

#5 · 3.5 / 5

Brevo

Best for marketers who want a full suite

A marketing suite with email, SMS, WhatsApp, a CRM and automation, plus a transactional API and SMTP relay. Its free plan sends the most email here.

Pros

The largest free volume: 300 emails a day
CRM, landing pages and automation built in
Paid plans sized by email volume, from $9 a month

Cons

SMS and WhatsApp credits are bought separately
A large step in price from Standard to Professional

Free plan: 300 emails a day
Paid from: $9 a month for 5,000 emails
Priced by: Emails sent

Unitpost vs Brevo Visit Brevo

#6 · 3.5 / 5

Amazon SES

Best for lowest cost at very high volume

Amazon's sending service, inside AWS: the lowest price per email here. You build the rest yourself, from bounce handling to templates and dashboards.

Pros

$0.10 per 1,000 emails on pay-as-you-go pricing
Runs inside your AWS account and IAM
Inbound email as well as sending

Cons

No campaign builder or audience tools
Bounce handling, dashboards and reputation work are yours

Free plan: None for SES; new AWS accounts get up to $200 in credits
Paid from: $0.10 per 1,000 emails (new accounts start on a $0.16 plan)
Priced by: Emails sent

Visit Amazon SES

#7 · 3.4 / 5

MailerSend

Best for a cheap first paid plan

A transactional email API with an official hosted MCP server and a $7 first paid plan. The free plan is small.

Pros

Hobby is $7 a month for 5,000 emails
API and SMTP on the free plan
An official hosted MCP server

Cons

500 emails a month on free
No audience or campaign tools

Free plan: 500 emails a month, card required
Paid from: $7 a month for 5,000 emails
Priced by: Emails sent

Visit MailerSend

#8 · 3.2 / 5

SendGrid

Best for enterprises and multi-tenant platforms

The long-running email API, now part of Twilio, with Marketing Campaigns as a separate product. Strong at scale; there is no free plan any more.

Pros

Proven at very high volume
Sub-accounts for multi-tenant platforms
Dedicated IPs from the Pro plan

Cons

No free plan: a 60-day trial, then from $19.95 a month
Marketing Campaigns is a separate product and plan

Free plan: None: a 60-day trial at 100 emails a day
Paid from: $19.95 a month (Essentials)
Priced by: Sends and contacts

Unitpost vs SendGrid Visit SendGrid

Scores side by side

Product	Deliverability30%	Developer experience25%	Free plan15%	Scale15%	First paid step15%	Total
Unitpost	3	5	5	2	5	4.0
Postmark	5	4	2	3	3	3.7
Resend	3	5	4	3	3	3.7
Mailgun	4	3	3	5	3	3.6
Brevo	3	3	5	3	4	3.5
Amazon SES	3	3	2	5	5	3.5
MailerSend	3	4	2	3	5	3.4
SendGrid	4	3	1	5	2	3.2

How we scored

This list is for developers sending the email an app can't work without: receipts, password resets, sign-in codes and alerts. Deliverability is weighted highest, then the API, then what you pay to start and to grow.

Deliverability (30%). A long public record of inbox placement for transactional mail, and the tooling to protect it.
Developer experience (25%). A clear REST API, current SDKs, readable errors and docs.
Free plan (15%). A permanent free plan large enough to run a small app on, with no card.
Scale (15%). Proven at very high volume, with dedicated IPs and enterprise plans.
First paid step (15%). A cheap first paid plan that grows with sends.

Each product gets 1 to 5 per criterion, from its own pricing and docs pages. The total is the weighted mean, so changing a weight re-ranks the list.

Why Unitpost scored 4.0

Deliverability: 3/5. Guided SPF, DKIM and DMARC with continuous checks, but a short public record so far.
Developer experience: 5/5. Bearer-token REST API, nine SDKs, a CLI and an MCP server, with idempotency keys on sends.
Free plan: 5/5. 5,000 emails a month free for good, 200 a day, no card.
Scale: 2/5. No sub-accounts, and dedicated IPs are not launched yet.
First paid step: 5/5. $10 a month for 20,000 emails, priced by sends.

Checked November 2, 2026 against unitpost.com/pricing, unitpost.com/sms, registry.npmjs.org/unitpost.

Why Postmark scored 3.7

Deliverability: 5/5. A long public record of time-to-inbox, protected by separate streams.
Developer experience: 4/5. A mature, well-documented API with official libraries.
Free plan: 2/5. 100 emails a month free, enough to test, not to run an app.
Scale: 3/5. Handles large volume; dedicated IPs from 300,000 emails a month on Pro and above.
First paid step: 3/5. Basic is $15 a month for 10,000 emails.

Checked November 2, 2026 against postmarkapp.com/pricing, postmarkapp.com/migration-guides, postmarkapp.com/lp/mcp, postmarkapp.com/developer/user-guide/send-email-with-smtp, registry.npmjs.org/postmark, postmarkapp.com/developer/webhooks/inbound-webhook.

Why Resend scored 3.7

Deliverability: 3/5. A shorter public record than SendGrid or Postmark.
Developer experience: 5/5. The API many newer providers copy, with SDKs across most languages.
Free plan: 4/5. 3,000 emails a month free, capped at 100 a day.
Scale: 3/5. Higher-volume plans above Pro; less proven at the very largest volumes.
First paid step: 3/5. Pro is $20 a month for 50,000 emails; marketing contacts are a second plan.

Checked November 2, 2026 against resend.com/pricing, resend.com/migrate, resend.com/docs/dashboard/receiving/introduction, github.com/resend/mcp-send-email, resend.com/docs/send-with-smtp, resend.com/docs/api-reference/api-keys/create-api-key, registry.npmjs.org/resend, resend.com/docs/dashboard/webhooks/retries-and-replays.

Why Mailgun scored 3.6

Deliverability: 4/5. Validation, inbox placement tests and dedicated IPs.
Developer experience: 3/5. A capable API on HTTP Basic auth, with a surface shaped by long history.
Free plan: 3/5. A free plan of 100 emails a day on one domain, with one day of logs.
Scale: 5/5. Built for very high volume, with dedicated IP pools and enterprise plans.
First paid step: 3/5. Basic from $15 a month for 10,000 emails.

Checked November 2, 2026 against mailgun.com/pricing/, mailgun.com/resources/guides/migrating-from-sendgrid-to-mailgun-email-api/, documentation.mailgun.com/docs/mailgun/mcp, documentation.mailgun.com/docs/mailgun/user-manual/sending-messages/send-smtp, registry.npmjs.org/mailgun.js, documentation.mailgun.com/docs/mailgun/user-manual/receive-forward-store/receive-http.

Why Brevo scored 3.5

Deliverability: 3/5. An established sender, without Postmark's public time-to-inbox record.
Developer experience: 3/5. A full API and SMTP relay, shaped by the marketing suite rather than built for developers first.
Free plan: 5/5. 300 emails a day, about 9,000 a month, on a permanent free plan.
Scale: 3/5. Professional plans from 150,000 emails; the focus is marketing teams more than high-volume APIs.
First paid step: 4/5. Starter from $9 a month, sized by email volume.

Checked November 2, 2026 against brevo.com/pricing/, developers.brevo.com/docs/mcp-protocol, help.brevo.com/hc/en-us/articles/7959631848850, help.brevo.com/hc/en-us/articles/360021533839, registry.npmjs.org/@getbrevo/brevo.

Why Amazon SES scored 3.5

Deliverability: 3/5. Good infrastructure, but reputation monitoring is your job.
Developer experience: 3/5. AWS SDKs and IAM: powerful, with more setup than an email API.
Free plan: 2/5. No SES free tier; new AWS accounts get up to $200 in credits.
Scale: 5/5. AWS-scale throughput and dedicated IPs.
First paid step: 5/5. Pay per email from $0.10 per 1,000, with no monthly minimum.

Checked November 2, 2026 against aws.amazon.com/ses/pricing/, docs.aws.amazon.com/ses/latest/dg/smtp-connect.html, docs.aws.amazon.com/ses/latest/dg/smtp-credentials.html, docs.aws.amazon.com/ses/latest/dg/vdm-dashboard.html, registry.npmjs.org/@aws-sdk/client-sesv2, docs.aws.amazon.com/ses/latest/dg/receiving-email-notifications-contents.html.

Why MailerSend scored 3.4

Deliverability: 3/5. An established sender, without a long public inbox-placement record.
Developer experience: 4/5. A modern REST API, SMTP and an official MCP server.
Free plan: 2/5. 500 emails a month on one domain.
Scale: 3/5. Plans for growing volume; fewer enterprise tools than the incumbents.
First paid step: 5/5. Hobby is $7 a month for 5,000 emails.

Checked November 2, 2026 against mailersend.com/pricing, developers.mailersend.com/mcp, mailersend.com/help/smtp-relay, mailersend.com/features/inbound-emails, developers.mailersend.com/api/v1/webhooks.html, registry.npmjs.org/mailersend, developers.mailersend.com/api/v1/inbound.

Why SendGrid scored 3.2

Deliverability: 4/5. A long track record, with dedicated IPs from the Pro plan.
Developer experience: 3/5. A large API with SDKs, shaped by a decade of backwards compatibility.
Free plan: 1/5. No free plan: a 60-day trial at 100 emails a day, then from $19.95 a month.
Scale: 5/5. Proven at very high volume, with sub-accounts and enterprise support.
First paid step: 2/5. Plans start at $19.95 a month (Essentials) once the 60-day trial ends.

Checked November 2, 2026 against twilio.com/en-us/products/email-api/pricing, twilio.com/docs/sendgrid/for-developers/sending-email/integrating-with-the-smtp-api, twilio.com/docs/sendgrid/ui/analytics-and-reporting/email-activity-feed, registry.npmjs.org/@sendgrid/mail, twilio.com/docs/sendgrid/for-developers/parsing-email/inbound-email.

Frequently asked questions

What is a transactional email service?

A service that sends the one-to-one email an app triggers: receipts, password resets, sign-in codes, alerts. It's sent because of something the person did, so it needs no marketing consent, but it must arrive in seconds and reach the inbox.

Can transactional and marketing email share one service?

Yes, if the service keeps them apart: separate streams, categories or sending subdomains, and an unsubscribe that stops marketing without stopping receipts. On Unitpost a template's category decides that, and topics let people opt out of updates and keep receipts.

Which transactional email service has the best deliverability?

Postmark publishes the longest public record of time to inbox for transactional mail. Deliverability depends more on your own domain setup, list hygiene and complaint rate than on the provider, so authenticate your domain and watch bounces whichever you choose.

Go deeper: Free email APIs · SMTP relay services · Domain checker · Idempotency

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