Transactional email

33 services

Transactional email services send the messages an application triggers itself: sign-up confirmations, password resets, receipts and alerts. They offer an HTTP API, an SMTP relay or both, and handle SPF, DKIM and bounce processing. Resend, Postmark, MailerSend and Mailjet are common choices; Brevo and Mailtrap also include marketing campaigns, and Amazon SES is the low-level option inside AWS.

Watch whether the quota is daily or monthly. Brevo lists 9,000 emails a month but caps sending at 300 a day; Resend gives 3,000 a month with 100 a day; Mailjet 6,000 a month and 200 a day. Sweego and ZeroSMTP set only daily caps, of 100 and 200. A daily cap can block a burst of sign-ups even when the monthly total is far from used.

Postmark allows only 100 emails a month, enough to test but not to run a product, and Amazon SES offers 3,000 messages a month for the first 6 months. Most providers require a verified custom domain, some limit how many you add, and new accounts may be reviewed before full sending is enabled. For inbound mail, Conduit and KaiMail forward received messages to a webhook.

33 services

AhaSend

Transactional email sending service with webhooks and inbound routing.

1,000 emails/mo

Unlimited domains, Unlimited team members

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Amazon SES

Transactional and bulk email sending over API or SMTP from AWS.

  • Expires

3,000 messages/mo

6 months

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Anypost

Email API for transactional and bulk sends.

3,000 emails/mo

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Brevo

Email platform covering transactional sends over API or SMTP plus marketing campaigns and contact lists.

9,000 emails/mo

300 emails/day

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Courier

Notification API with templates that routes one call to email, SMS, push, chat or in-app inboxes.

10,000 messages/mo

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EmailJS

Client-side email sending from browser JavaScript using stored templates, no backend required.

200 requests/mo

2 templates, 50 KB per request

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EmailLabs.io

Transactional email delivery service with SMTP and API sending.

9,000 emails/mo

300 emails/day

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Emitlo

Sending service offering both an HTTP API and SMTP relay with SPF/DKIM/DMARC support.

  • No card

12,000 emails/mo

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KaiMail

Custom-domain forwarding with ARC and DKIM signing, plus webhooks for incoming mail.

300 emails/mo

1 domain, 1 mailbox, 1 MB message size

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MailChannels

Outbound sending service reachable over a REST API or SMTP.

3,000 emails/mo

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Maileroo

Developer sending platform with SMTP relay, HTTP API, verification and blocklist checks.

5,000 emails/mo

Unlimited domains

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MailerSend

Transactional sending platform with an HTTP API and SMTP relay.

500 emails/mo

100 API requests/day

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Mailjet

Email delivery platform for transactional messages and marketing sends.

6,000 emails/mo

200 emails/day

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Mailtrap

Sending API and SMTP alongside marketing campaigns and a sandbox inbox for testing.

4,000 emails/mo

150 emails/day, 500 marketing contacts, 50 sandbox emails/mo

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OneSignal

Messaging platform for push notifications, in-app messages and email to app users.

  • No card

10,000 emails/mo

Unlimited push notifications, Unlimited contacts

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Pharos

Transactional sending via HTTP API or SMTP relay for application mail.

3,000 emails/mo

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Plunk

Email platform for sending application messages from code.

3,000 emails/mo

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Postmark

Transactional delivery service for app mail, plus weekly DMARC summary reports.

100 emails/mo

Unlimited DMARC digests

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Reloop

Sending API and SMTP for app mail, including an inbox meant for AI agents.

3,000 emails/mo

200 emails/day, 1 custom domain, 1 agent inbox

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Resend

Developer API for sending application email with SDKs for common languages.

3,000 emails/mo

100 emails/day, 1 custom domain

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SendRaven

Sending API for app mail that also receives replies and keeps threaded conversations for agents.

3,000 emails/mo

Unlimited contacts, Unlimited inbound replies

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SendStreak

Templating, automation and send-history layer that sits on top of an SMTP server you supply.

100 emails/day

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SMTPfast

Lightweight sending API for developers to deliver app mail.

  • No card

3,000 emails/mo

1 domain, 1,000 contacts

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Sweego

EU-based transactional sending API for application email.

100 emails/day

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Unitpost

Email sending API for transactional and marketing mail, with SDKs and an MCP server.

  • No card

5,000 emails/mo

200 emails/day, 10,000 contacts, 5 domains

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Wraps

Dashboard and tooling that runs mail sending on Amazon SES inside your own AWS account.

1 AWS account

Unlimited domains

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ZeroSMTP5

Shared SMTP relay sending from a common msgwing.com address, with setup samples in many languages.

200 emails/day

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Conduit

Inbound email bridge that forwards each received message to your endpoint as a webhook.

Limits not listed

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Parsio.io

Inbound parser that pulls structured fields out of forwarded messages and posts them onward.

Limits not listed

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