Best Transactional Email Services: 8 Options Compared
A transactional email service sends the messages your application triggers for one recipient at a time: password resets, receipts, verification codes, and account notifications. Choosing one means comparing deliverability controls, template workflow, event webhooks, suppression handling, and whether marketing email lives in the same product or a second tool.
Loops is our product, and it appears first on this list. Provider descriptions were reviewed in July 2026. The pricing comparison was checked on September 21, 2026. Confirm plan limits and rates before buying.
What a transactional email service does
Transactional email is triggered by something a specific user did or needs: a signup to verify, a purchase to confirm, a password to reset. These messages still go to people who unsubscribed from marketing, so providers treat transactional traffic separately from bulk sending. Our transactional email overview covers how that separation works in practice.
The service’s job is everything around the trigger call: authenticated sending infrastructure, templates, delivery and engagement events, bounce and complaint handling, and logs you can search when a user says the reset email never arrived. The gap between services is mostly in how much of that operational work they do for you, which is what our transactional email best practices guide is about.
8 transactional email services compared
Service
Best for
Loops
SaaS teams that want all email in one product
Postmark
Teams that want message types kept strictly separate
Resend
API-first teams managing templates in code
SendGrid (Twilio)
High-volume teams needing a broad integration surface
Amazon SES
AWS teams that want infrastructure control
Mailgun (Sinch)
Products that receive and route email
Brevo
Teams combining email with SMS and other channels
Mailchimp Transactional
Teams already running marketing in Mailchimp
Types and use cases come from each provider’s current documentation.
Monthly cost at 10,000 and 50,000 emails
Checked September 21, 2026. Prices are in USD, billed monthly, before taxes, promotions and optional extras. These plans have different contact limits and features; the assumptions below matter as much as the price.
Service
10k / month
50k / month
Loops: the $49 plan covers up to 5,000 subscribed contacts, with unlimited sends and transactional recipients outside your audience. A larger subscribed audience costs more.
Postmark: Basic at each volume. Resend: Pro includes 50,000 emails. SendGrid: Essentials includes 50,000 emails. Check overage rates and retention limits; marketing tools may require a separate plan.
Amazon SES: Essentials at $0.16 per 1,000 emails. The à-la-carte option starts at $0.10 per 1,000 ($1 and $5 at these volumes). Attachment data, optional services and your engineering costs are separate.
Mailgun: Basic for 10,000 emails and Foundation for 50,000. The plans differ in domain limits and log retention, as well as send volume.
Brevo: Starter, with a shared marketing and transactional email allowance. The selected tiers allow 1,500 and 500,000 stored contacts respectively. Removing Brevo branding adds $12 per month. SMS credits are separate.
Mailchimp: one or two prepaid 25,000-email blocks at $20 each, plus a required Standard or Premium marketing plan (or an eligible legacy Monthly Plan). The table is not the total Mailchimp bill.
1. Loops
Loops sends transactional email through an API and SMTP alongside campaigns and event-driven workflows. Templates are designed in the same editor as marketing email, published, then triggered from code with a transactional ID and data variables. Contacts, suppressions, and sending infrastructure are shared across every message type, so a hard bounce recorded on a receipt also stops a newsletter.
Shortlist Loops if your product needs password resets, receipts, and lifecycle email without running two tools with two contact models. Applications that need raw MIME control, inbound mail processing, or an AWS-native permission model should use a lower-level infrastructure service.
2. Postmark
Postmark sends through an HTTP API or SMTP, and its Message Streams model makes separation explicit: transactional, broadcast, and inbound traffic each run on their own stream with their own rules. Templates, test tokens, delivery events, and inbound parsing are part of the product.
Shortlist Postmark if you want the service itself to enforce the boundary between message types. Confirm stream limits, subscription handling on broadcast streams, and whether your plan includes inbound processing.
Moving your email to Loops? See the Postmark migration guide.
3. Resend
Resend is a developer-focused sending API with official SDKs and templates managed in the dashboard or written in code. A send can reference a published template and pass variables, or provide the message content directly.
Shortlist Resend if your team wants a focused API and treats email templates as part of the codebase. Confirm how far its marketing and audience features go before consolidating on it, and check the SDK, webhook, and account controls your application needs.
4. SendGrid (Twilio)
Twilio SendGrid runs transactional sending through its Mail Send API, with marketing tools in a separate Marketing Campaigns product. The platform includes high-volume options like dedicated IPs.
Existing Twilio customers should map which capabilities belong to which product and which plan includes the support they need. To move from SendGrid to Loops, follow our SendGrid migration guide.
5. Amazon SES
Amazon SES is email infrastructure: API and SMTP sending, simple or raw MIME message construction, and AWS IAM control over which identities can send. Compare its usage-based sending charges with the cost of the AWS services and operational work your implementation needs.
The tradeoff is operational: production access requests, configuration sets, bounce and complaint processing, templates, suppression management, and monitoring all land in your implementation plan. Shortlist SES if your team is AWS-native and wants that control.
6. Mailgun (Sinch)
Mailgun supports REST and SMTP sending in US and EU regions. For inbound email, Routes can run multi-step rules on received mail, and a Forwards API handles simpler recipient-based forwarding.
Mailgun fits products that receive and route email as well as send it. Compare region selection, log retention, suppression behavior, and event access on the plan you would actually buy.
To move sending to Loops, use the Mailgun migration guide. Keep Mailgun or another service for inbound routing.
7. Brevo
Brevo exposes one REST API for transactional email, SMS, WhatsApp, contacts, custom events, and ecommerce data. Transactional email is one channel in a broader contact and messaging system.
Shortlist Brevo if email sits alongside other channels in your product’s communication plan. Confirm the contact model, daily send caps on lower tiers, and the boundary between API sending and marketing automation.
The Brevo migration guide covers moving email to Loops. Keep a separate provider for SMS and WhatsApp.
8. Mailchimp Transactional
Mailchimp Transactional, formerly Mandrill, is a paid add-on to Mailchimp marketing plans rather than a standalone service. It suits teams whose marketing already runs in Mailchimp and who want transactional sending attached to the same account.
Verify the add-on’s block-based pricing at your volume, and check how templates, suppressions, and contact data move between the transactional add-on and the main Mailchimp product, since Mailchimp operates them as distinct systems.
How to choose a transactional email service
Decide whether transactional and marketing email should live in one product with one contact model or stay deliberately separate. Choose who edits templates: developers in code, or the wider team in an editor. Then compare event webhooks, suppression behavior, log retention, data regions, and what the service does when a message bounces. Check the authentication requirements of your sending service and the receiving providers you send to. Our email deliverability guide covers the parts that stay your job.
If the API contract matters as much as the service, our email API comparison looks at the same market from the developer’s side: request shapes, SDKs, idempotency, and template workflow. Run the same password-reset and receipt flow through your final two candidates before committing.
Frequently asked questions
What is a transactional email service?
Can one service handle transactional and marketing email?
Do transactional emails need an unsubscribe link?
Should transactional email be separated from marketing email?
Related: our email API comparison for developers, transactional email best practices, and the transactional email overview.