--- title: "Best transactional email services in 2026" description: "Transactional email services ranked for receipts, password resets and sign-in codes: deliverability, the API, the free plan, scale and the first paid step." url: https://www.unitpost.com/best/transactional-email-services section: Roundups updated: 2026-11-02 --- # 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 2026-11-02. 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. ## At a glance | # | 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 ## 1. 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. Website: https://www.unitpost.com ## 2. 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. Website: https://postmarkapp.com ## 3. 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. Website: https://resend.com ## 4. 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. Website: https://www.mailgun.com ## 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. Website: https://www.brevo.com ## 6. 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. Website: https://aws.amazon.com/ses/ ## 7. 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. Website: https://www.mailersend.com ## 8. 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. Website: https://www.twilio.com/en-us/sendgrid ## Scores | Product | Deliverability (30%) | Developer experience (25%) | Free plan (15%) | Scale (15%) | First paid step (15%) | 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; the total is the weighted mean. ### 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 2026-11-02 against https://www.unitpost.com/pricing, https://www.unitpost.com/sms, https://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 2026-11-02 against https://postmarkapp.com/pricing, https://postmarkapp.com/migration-guides, https://postmarkapp.com/lp/mcp, https://postmarkapp.com/developer/user-guide/send-email-with-smtp, https://registry.npmjs.org/postmark, https://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 2026-11-02 against https://resend.com/pricing, https://resend.com/migrate, https://resend.com/docs/dashboard/receiving/introduction, https://github.com/resend/mcp-send-email, https://resend.com/docs/send-with-smtp, https://resend.com/docs/api-reference/api-keys/create-api-key, https://registry.npmjs.org/resend, https://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 2026-11-02 against https://www.mailgun.com/pricing/, https://www.mailgun.com/resources/guides/migrating-from-sendgrid-to-mailgun-email-api/, https://documentation.mailgun.com/docs/mailgun/mcp, https://documentation.mailgun.com/docs/mailgun/user-manual/sending-messages/send-smtp, https://registry.npmjs.org/mailgun.js, https://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 2026-11-02 against https://www.brevo.com/pricing/, https://developers.brevo.com/docs/mcp-protocol, https://help.brevo.com/hc/en-us/articles/7959631848850, https://help.brevo.com/hc/en-us/articles/360021533839, https://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 2026-11-02 against https://aws.amazon.com/ses/pricing/, https://docs.aws.amazon.com/ses/latest/dg/smtp-connect.html, https://docs.aws.amazon.com/ses/latest/dg/smtp-credentials.html, https://docs.aws.amazon.com/ses/latest/dg/vdm-dashboard.html, https://registry.npmjs.org/@aws-sdk/client-sesv2, https://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 2026-11-02 against https://www.mailersend.com/pricing, https://developers.mailersend.com/mcp, https://www.mailersend.com/help/smtp-relay, https://www.mailersend.com/features/inbound-emails, https://developers.mailersend.com/api/v1/webhooks.html, https://registry.npmjs.org/mailersend, https://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 2026-11-02 against https://www.twilio.com/en-us/products/email-api/pricing, https://www.twilio.com/docs/sendgrid/for-developers/sending-email/integrating-with-the-smtp-api, https://www.twilio.com/docs/sendgrid/ui/analytics-and-reporting/email-activity-feed, https://registry.npmjs.org/@sendgrid/mail, https://www.twilio.com/docs/sendgrid/for-developers/parsing-email/inbound-email. ## FAQ ### 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. ## Related - [Best email APIs for Node.js in 2026](https://www.unitpost.com/best/email-apis-for-nodejs): Email APIs ranked for Node.js and TypeScript: the official SDK and its types, the API, the free plan, deliverability and the first paid step, from npm data. - [Best inbound email parsing services in 2026](https://www.unitpost.com/best/inbound-email-parsing): Inbound email parsing services ranked: the parsed message and its verdicts, how deliveries are signed and retried, and receiving on the free plan. - [Best email APIs for AI agents in 2026](https://www.unitpost.com/best/email-apis-for-ai-agents): Email APIs ranked for AI agents: official MCP servers, send safety, reading replies, agent-readable docs and the free plan. With the reasons for every score.