Starter
For your first email program.
$16USD / month
$192 billed yearly.
20,000 emails / month
Choose Starter- 5 brands · 3 seats
- 5 custom sending domains
- 500 email verifications/month
- $1.50 / 1,000 extra emails
Nitrosend is the best free email API for AI agents of the ten reviewed here, with the top score of 83.75 out of 100. It scores 9 out of 10 on working from your AI assistant, the test worth the most points. Its free plan gives 5,000 emails to start and then 500 every month, with no card and no expiry, and full API, MCP and CLI access. To send email from an AI agent with Nitrosend, add its MCP server at api.nitrosend.com/mcp in Claude, ChatGPT, Cursor or Codex and sign in through the browser, which also creates the free account. The agent can then switch on a ready sender with no DNS records and send, and every email comes out in your brand. It is the only one of the ten where an assistant gets from sign-up to a delivered email without anyone opening a dashboard. A receipt or password reset goes out on the call, and campaigns and flows stay drafts until approved. AgentMail also lets an agent sign itself up, but a person has to enter a one-time code before it can email anyone else. When you outgrow it, the next step is $20 a month for 20,000 emails. Resend comes next at 77.5, then Brevo at 70.
Free email APIs with no credit card: Nitrosend, Brevo, Mailjet, Postmark and AgentMail say so on their own pages, while MailerSend's free plan asks for a card. On Nitrosend's Free plan, the 5,000 starting emails sit alongside a daily limit: you can send to between 100 and 5,000 recipients in any rolling 24 hours, depending on your sender standing.
The ranking
Rank 1Nitrosend
83.75 out of 100Total
- Priced by
- Emails sent
- Free plan
- 5,000 emails, then 500 a month
- Entry plan
- $20 a month, 20,000 emails
- Works from your AI assistant9 out of 10Official MCP server, account signup over the API and a ready-made sender, so an agent sends with no dashboard (docs).
- Receipts and newsletters on one plan9 out of 10Receipts, campaigns and flows share one plan, one API and one allowance, on separate streams (pricing).
- Emails in your brand, no designer9 out of 10Brand Kit reads your site for logo, colors, fonts and voice, and every drafted email uses it (docs).
- Free plan7 out of 105,000 emails up front, then 500 every month, no card and no expiry (pricing).
- Price8.5 out of 10$20 a month for 20,000 emails on Starter and $650 for a million emails on Scale including overage, with unlimited contacts on every plan (pricing).
- Developer tools10 out of 10REST API with an OpenAPI spec, a typed TypeScript SDK, a CLI, an MCP server, signed event webhooks, idempotent sends and test sends (docs).
- Track record and support4 out of 10A young product from a small team. Dedicated IPs available as a provisioned add-on on Scale or Enterprise, a 99.9% SLA only on Enterprise (pricing).
Nitrosend
Ask your agent for the next campaign
Connect Nitrosend to Claude, ChatGPT, Cursor or Codex, point Brand Kit at your site, and describe the email. Contacts are unlimited on every plan.
Free: 5,000 emails to start, then 500 a month. No credit card.
Start free
Rank 2Resend
77.5 out of 100Total
- Priced by
- Emails sent, plus contacts for marketing
- Free plan
- 3,000 emails a month, 100 a day
- Entry plan
- $20 a month, 50,000 emails
- Works from your AI assistant8 out of 10Hosted MCP server with OAuth, plus agent plugins and a CLI, but a person creates the account and verifies a domain (docs).
- Receipts and newsletters on one plan7 out of 10Broadcasts and automations share the account and API, but marketing is a second plan priced by contacts (pricing).
- Emails in your brand, no designer6 out of 10An AI writer in the editor with URL and brand analysis listed, and React Email for coded templates (pricing).
- Free plan8 out of 103,000 emails a month, up to 100 a day, on a free plan that does not expire (pricing).
- Price9 out of 10$20 a month for 20,000 emails on Pro, the same as Nitrosend, but $650 for a million on Scale (pricing).
- Developer tools9 out of 10Official SDKs, an SMTP relay, webhooks, inbound email, React Email and a CLI on every plan (pricing).
- Track record and support6 out of 10Newer than the incumbents, with SOC 2 Type II, dedicated IPs on Scale and a 99.99% SLA on Enterprise (pricing).
Rank 3Brevo (formerly Sendinblue)
70 out of 100Total
- Priced by
- Emails sent
- Free plan
- 300 emails a day, no expiry
- Entry plan
- Starter, $9 a month, 5,000 emails
- Works from your AI assistant5 out of 10Hosted MCP server at mcp.brevo.com with a token a person creates, but its modules list no tool that sends a transactional email (docs).
- Receipts and newsletters on one plan8 out of 10Transactional email by API and SMTP on every plan, counted in the same monthly volume as campaigns, with automation from Standard (pricing).
- Emails in your brand, no designer7 out of 10The brand library fetches a logo, colors, fonts and social links from your website into the email editor, but not a tone of voice (help).
- Free plan9 out of 10300 emails a day, about 9,000 a month, with transactional email and up to 100,000 contacts, free forever (help).
- Price6 out of 10$69 a month for 20,000 emails on Standard, the first plan with automated emails (Starter is $32 without them), and $999 for a million on Professional (pricing).
- Developer tools9 out of 10Official SDKs in seven languages, an SMTP relay, transactional webhooks, a sandbox header and inbound email parsing (docs).
- Track record and support7 out of 10Sending since 2012 as Sendinblue. Dedicated IPs are an add-on from Professional, and an SLA comes only with Enterprise (help).
Rank 4MailerSend
68.5 out of 100Total
- Priced by
- Emails sent
- Free plan
- 500 emails a month, card required
- Entry plan
- $7 a month, 5,000 emails (Hobby)
- Works from your AI assistant8 out of 10Hosted MCP server connected by OAuth that sends and schedules email, sets up domains and webhooks and reads email activity, once a person has signed up (docs).
- Receipts and newsletters on one plan4 out of 10Bulk emailing through the same API, but no campaign builder, segments or automation flows (pricing).
- Emails in your brand, no designer6 out of 10Drag-and-drop, HTML and rich-text builders with ready-made templates, which you still set up in your brand (pricing).
- Free plan5 out of 10A Free plan of 500 emails a month with 100 API requests a day, and a card on file (pricing).
- Price8 out of 10$35 a month for 20,000 emails on Starter, which covers 50,000, and $600 for a million on Starter (pricing).
- Developer tools9 out of 10Seven SDKs, an OpenAPI collection, SMTP relay, webhooks, inbound routing and testing features (pricing).
- Track record and support6 out of 10A 99.5% uptime SLA on its top plans, with dedicated IPs on Enterprise above 100,000 emails a week (pricing).
Rank 5Mailgun
67.5 out of 100Total
- Priced by
- Emails sent
- Free plan
- 100 emails a day
- Entry plan
- $15 a month, 10,000 emails
- Works from your AI assistant6 out of 10Official MCP server for sends, analytics and validation, run locally with an API key. Mailgun offers no hosted version (docs).
- Receipts and newsletters on one plan4 out of 10Mailing lists and a template builder on the sending API, but no campaign builder or automation flows (pricing).
- Emails in your brand, no designer5 out of 10An email template builder and templates API, but the brand design is yours to build (pricing).
- Free plan7 out of 10A free plan of 100 emails a day, one sending domain and one inbound route (pricing).
- Price8 out of 10$33 a month for 20,000 emails on Basic with overage, and $700 for a million on Scale (pricing).
- Developer tools9 out of 10Official SDKs in six languages, SMTP relay, webhooks, inbound routes and a validation API (docs).
- Track record and support9 out of 10A long-running sending API, now part of Sinch, with dedicated IP pools, IP warm-up and an uptime SLA (pricing).
Rank 6Amazon SES
65.5 out of 100Total
- Priced by
- Emails sent
- Free plan
- None. New AWS customers get up to $200 in credits
- Entry price
- $0.10 per 1,000 emails, or $0.16 on Essentials
- Works from your AI assistant7 out of 10AWS's own managed MCP server runs SES API calls, so an agent can send and read sending data, but it connects with IAM credentials a person sets up, and new accounts start in the SES sandbox (AWS).
- Receipts and newsletters on one plan3 out of 10A sending service with contact lists and subscription management, but no campaign builder or automation flows (pricing).
- Emails in your brand, no designer2 out of 10Stored templates are HTML and text you write yourself. There is no visual editor and no brand setup (pricing).
- Free plan4 out of 10No standing free plan. New AWS customers get up to $200 in Free Tier credits that apply to SES (pricing).
- Price10 out of 10Metered at $0.16 per 1,000 on Essentials, so $3.20 for 20,000 emails and $160 for a million (pricing).
- Developer tools9 out of 10AWS SDKs in every major language, SMTP, event publishing, inbound receiving and a mailbox simulator for tests (docs).
- Track record and support9 out of 10Running at Amazon scale since 2011, with managed dedicated IPs, Virtual Deliverability Manager and tenant isolation (pricing).
Rank 7Postmark
64.5 out of 100Total
- Priced by
- Emails sent
- Free plan
- 100 emails a month, no expiry
- Entry plan
- $15 a month, 10,000 emails
- Works from your AI assistant6 out of 10Official MCP server with 24 tools, run locally with a server token a person creates first (Postmark).
- Receipts and newsletters on one plan4 out of 10Broadcast streams send bulk mail from the same account, but there is no campaign builder or flows (docs).
- Emails in your brand, no designer5 out of 10A library of ready-made transactional templates, which you still edit into your own brand (Postmark).
- Free plan4 out of 10A free Developer plan of 100 emails a month that never expires, for testing (pricing).
- Price8 out of 10$29.50 a month for 20,000 emails on Pro with overage, and $775 on Basic for the 1.5 million step (pricing).
- Developer tools9 out of 10Official libraries for Node.js and TypeScript, Python, Ruby, .NET, Java and PHP, SMTP, delivery and bounce webhooks, and inbound processing (docs).
- Track record and support9 out of 10A transactional specialist since 2010, with separate streams, managed dedicated IPs and 45-day retention (pricing).
Rank 8Mailjet (Sinch)
62.5 out of 100Total
- Priced by
- Emails sent
- Free plan
- 6,000 emails a month, 200 a day, no expiry
- Entry plan
- Starter, $9 a month, 8,000 emails
- Works from your AI assistant3 out of 10Official MCP server runs on your own computer and registers only read (GET) tools, so an agent cannot send through it (GitHub).
- Receipts and newsletters on one plan8 out of 10Send API, SMTP relay and campaigns share one plan and one email volume, but automations need Premium (pricing).
- Emails in your brand, no designer7 out of 10Brand Kit suggests colors and themes from your website URL and applies them to marketing, transactional and automation templates on paid plans, not voice (help).
- Free plan8 out of 106,000 emails a month, at most 200 a day, up to 1,000 contacts, with the APIs and SMTP relay included and no card (pricing).
- Price6 out of 10$41.90 for 20,000 emails on Premium 15,000 at $29 plus $2.58 per 1,000 after (Premium 50,000 is $59, Essential has no automations), and $1,099 for a million on Premium 500,000 plus overage, or a custom quote (pricing, overage).
- Developer tools8 out of 10Official SDKs in seven languages, SMTP relay, event webhooks, a sandbox mode and the Parse API for inbound, which needs Premium 50k or above (docs).
- Track record and support7 out of 10Sending since 2010, now part of Sinch. A dedicated IP on Premium from 100,000 emails, and an SLA only on custom plans (pricing).
Rank 9SendGrid
59.5 out of 100Total
- Priced by
- Emails sent (Email API)
- Free plan
- Trial: 100 a day for 60 days
- Entry plan
- $19.95 a month, 50,000 emails
- Works from your AI assistant3 out of 10No first-party SendGrid MCP server. Twilio's beta MCP server searches API docs and does not send (Twilio).
- Receipts and newsletters on one plan6 out of 10Marketing Campaigns is a separate product with its own plan, priced on contacts stored (Twilio).
- Emails in your brand, no designer5 out of 10Dynamic templates, a design editor and a Designs API, but the design is yours to build (docs).
- Free plan3 out of 10A trial, not a plan: 100 emails a day for 60 days, then pay (pricing).
- Price9 out of 10$19.95 a month for 20,000 emails on Essentials, and $799 for the Pro 1.5 million step (pricing).
- Developer tools9 out of 10SDKs in seven languages, SMTP relay, event webhooks, Inbound Parse and a sandbox mode (docs).
- Track record and support8 out of 10Sending since 2009, owned by Twilio since 2019, dedicated IPs included on Pro (pricing).
Rank 10AgentMail
54 out of 100Total
- Priced by
- Inboxes and emails sent
- Free plan
- 3 inboxes, 3,000 emails a month, no card
- Entry plan
- $20 a month, 10 inboxes, 10,000 emails (Developer)
- Works from your AI assistant8 out of 10Hosted MCP server with OAuth and a sign-up API for agents, but a person must pass on a one-time code before the account can email anyone else (docs).
- Receipts and newsletters on one plan2 out of 10Built for two-way agent conversations. No campaigns, newsletters, segments or automation flows are documented (docs).
- Emails in your brand, no designer2 out of 10No email templates or brand tools are documented. The agent or developer writes every body (docs).
- Free plan7 out of 103 inboxes and 3,000 emails a month, 100 a day, no card, but no custom domain on the free plan (pricing).
- Price5 out of 10$40 a month for 20,000 emails on Developer with add-ons, and no public price for a million (pricing).
- Developer tools7 out of 10Python and Node SDKs, a CLI, SMTP and IMAP, delivery webhooks, WebSockets and first-class inbound, but no templates or test mode (docs).
- Track record and support4 out of 10Y Combinator-backed, with a $6M seed announced in March 2026. SOC 2, but dedicated IPs and an SLA only on Enterprise (pricing).
How they compare
How each one scores
Scores out of 10, September 26, 2026| What we compared | Nitrosend | Resend | Brevo | MailerSend | Mailgun | SES | Postmark | Mailjet | SendGrid | AgentMail |
|---|---|---|---|---|---|---|---|---|---|---|
| Works from your AI assistant25 points | 9 out of 10 | 8 out of 10 | 5 out of 10 | 8 out of 10 | 6 out of 10 | 7 out of 10 | 6 out of 10 | 3 out of 10 | 3 out of 10 | 8 out of 10 |
| Receipts and newsletters on one plan15 points | 9 out of 10 | 7 out of 10 | 8 out of 10 | 4 out of 10 | 4 out of 10 | 3 out of 10 | 4 out of 10 | 8 out of 10 | 6 out of 10 | 2 out of 10 |
| Emails in your brand, no designer10 points | 9 out of 10 | 6 out of 10 | 7 out of 10 | 6 out of 10 | 5 out of 10 | 2 out of 10 | 5 out of 10 | 7 out of 10 | 5 out of 10 | 2 out of 10 |
| Free plan10 points | 7 out of 10 | 8 out of 10 | 9 out of 10 | 5 out of 10 | 7 out of 10 | 4 out of 10 | 4 out of 10 | 8 out of 10 | 3 out of 10 | 7 out of 10 |
| Price15 points | 8.5 out of 10 | 9 out of 10 | 6 out of 10 | 8 out of 10 | 8 out of 10 | 10 out of 10 | 8 out of 10 | 6 out of 10 | 9 out of 10 | 5 out of 10 |
| Developer tools15 points | 10 out of 10 | 9 out of 10 | 9 out of 10 | 9 out of 10 | 9 out of 10 | 9 out of 10 | 9 out of 10 | 8 out of 10 | 9 out of 10 | 7 out of 10 |
| Track record and support10 points | 4 out of 10 | 6 out of 10 | 7 out of 10 | 6 out of 10 | 9 out of 10 | 9 out of 10 | 9 out of 10 | 7 out of 10 | 8 out of 10 | 4 out of 10 |
| Total scoreout of 100 | 83.75 out of 100,1st | 77.5 out of 100,2nd | 70 out of 100,3rd | 68.5 out of 100,4th | 67.5 out of 100,5th | 65.5 out of 100,6th | 64.5 out of 100,7th | 62.5 out of 100,8th | 59.5 out of 100,9th | 54 out of 100,10th |
Here are the seven yes-or-no questions developers usually ask before they start on a free plan. A tick means the service does it, as described on its own pages today. A dash means the answer is not a clean yes or no.
10 services, side by side
Checked September 26, 2026QuestionNitrosendResendBrevoMailerSendMailgunSESPostmarkMailjetSendGridAgentMail
NitrosendResendBrevoMailerSendMailgunSESPostmarkMailjetSendGridAgentMailSend from the chatCan an agent send a transactional email without anyone opening the web app?Nitrosend: Yes.Resend: Yes.Brevo: Not a yes or no.MailerSend: Yes.Mailgun: Yes.SES: Not a yes or no.Postmark: Yes.Mailjet: No.SendGrid: Not a yes or no.AgentMail: Yes.
| Service | Answer |
|---|---|
| Nitrosend | Yes. Yes, through the MCP server. A single transactional email sends on the call; campaigns and flows stay drafts until approved. |
| Resend | Yes. Yes, once a person has created the account and verified a sending domain. |
| Brevo | Not a yes or no. The hosted MCP server creates and manages campaigns, but no tool for sending a transactional email is documented. |
| MailerSend | Yes. Yes, once a person has signed up and authorized the MCP connection. |
| Mailgun | Yes. Yes, once a person has created the account and handed the MCP server an API key. |
| SES | Not a yes or no. Only through a sample or general AWS MCP server, with AWS credentials a person sets up. |
| Postmark | Yes. Yes, once a person has set up the account and handed the MCP server a server token. |
| Mailjet | No. No. The MCP server exposes only read endpoints, so it cannot send. |
| SendGrid | Not a yes or no. Only by writing code against the API. Twilio's own MCP server searches the docs and does not send. |
| AgentMail | Yes. Yes, through the hosted MCP server's send_message tool once an account exists. |
Hosted MCP serverCan a chat app connect over the web, with no local install?Nitrosend: Yes.Resend: Yes.Brevo: Yes.MailerSend: Yes.Mailgun: No.SES: No.Postmark: No.Mailjet: No.SendGrid: No.AgentMail: Yes.
| Service | Answer |
|---|---|
| Nitrosend | Yes. Yes. A remote server at api.nitrosend.com/mcp, with OAuth sign-in. |
| Resend | Yes. Yes. A remote server at mcp.resend.com/mcp, with OAuth sign-in. |
| Brevo | Yes. Yes. mcp.brevo.com, signed in with a token a person generates in the web app. |
| MailerSend | Yes. Yes. Connect by URL and authorize access to the account. |
| Mailgun | No. No. Mailgun's docs say the server runs locally and no hosted version exists. |
| SES | No. No hosted SES MCP server. |
| Postmark | No. No. The official server runs locally through npx with an API token. |
| Mailjet | No. No. The MCP server runs locally through npx with your API key. |
| SendGrid | No. No. Every SendGrid server on the official MCP registry is community built, none hosted by Twilio. |
| AgentMail | Yes. Yes. mcp.agentmail.to/mcp, with OAuth or an API key. |
Sign up with no personCan an agent create the account and send a first email with no DNS work?Nitrosend: Yes.Resend: No.Brevo: No.MailerSend: No.Mailgun: No.SES: No.Postmark: No.Mailjet: No.SendGrid: No.AgentMail: Not a yes or no.
| Service | Answer |
|---|---|
| Nitrosend | Yes. Yes. Signup is an API call, and each brand gets a ready sender on a Nitrosend subdomain. |
| Resend | No. No. Resend's own agent guide says a person must create the account. |
| Brevo | No. No. A person creates the account and the MCP token, and Brevo approves the account before it sends. |
| MailerSend | No. No. A person signs up, with a card even on Free, and verifies a domain. |
| Mailgun | No. No. A person signs up and verifies a sending domain first. |
| SES | No. No. A person opens the AWS account, verifies a domain and requests production access. |
| Postmark | No. No. A person signs up and confirms a sender signature or domain first. |
| Mailjet | No. No. A person signs up in the web app and copies the API keys. |
| SendGrid | No. No. A sender or a domain has to be verified before real sending. |
| AgentMail | Not a yes or no. An agent can sign itself up over the API, but a person must supply the emailed one-time code before it can send to anyone else. |
Campaigns and flows in the same planDo newsletters and automations come with the transactional plan?Nitrosend: Yes.Resend: Not a yes or no.Brevo: Yes.MailerSend: No.Mailgun: No.SES: No.Postmark: Not a yes or no.Mailjet: Not a yes or no.SendGrid: No.AgentMail: No.
| Service | Answer |
|---|---|
| Nitrosend | Yes. Yes, on every plan including Free. |
| Resend | Not a yes or no. Broadcasts and automations are in the same account, on a separate marketing plan. |
| Brevo | Yes. Yes. Transactional is on every plan and automation runs from Free up to 2,000 contacts and from Standard without a limit. |
| MailerSend | No. No. Bulk emailing, but no campaign builder or flows. |
| Mailgun | No. No. Mailing lists and templates, but no campaign builder or flows. |
| SES | No. No. SES sends, and the campaigns and flows are yours to build. |
| Postmark | Not a yes or no. Broadcast streams handle bulk sends. There is no campaign builder or automation flows. |
| Mailjet | Not a yes or no. Campaigns and the Send API share every plan, but flows start on Premium. |
| SendGrid | No. No. Marketing Campaigns is a separate plan, from $15 a month. |
| AgentMail | No. No campaigns, newsletters or automation flows are documented. |
Perpetual free planIs there a free plan that does not run out?Nitrosend: Yes.Resend: Yes.Brevo: Yes.MailerSend: Yes.Mailgun: Yes.SES: No.Postmark: Yes.Mailjet: Yes.SendGrid: No.AgentMail: Yes.
| Service | Answer |
|---|---|
| Nitrosend | Yes. Yes. 5,000 emails up front, then 500 a month. |
| Resend | Yes. Yes. 3,000 emails a month, 100 a day. |
| Brevo | Yes. Yes. 300 emails a day with no time limit. |
| MailerSend | Yes. Yes. 500 emails a month. |
| Mailgun | Yes. Yes. 100 emails a day. |
| SES | No. No. Up to $200 in AWS credits for new customers. |
| Postmark | Yes. Yes. 100 emails a month on the Developer plan, with no expiry. |
| Mailjet | Yes. Yes. 6,000 emails a month, 200 a day, no time limit. |
| SendGrid | No. No. 100 emails a day for 60 days, then a paid plan. |
| AgentMail | Yes. Yes. 3,000 emails a month at $0 with no card and no stated end date. |
Brand learned from your siteDoes it pick up your logo, colors, fonts and voice without a designer?Nitrosend: Yes.Resend: Not a yes or no.Brevo: Yes.MailerSend: No.Mailgun: No.SES: No.Postmark: No.Mailjet: Yes.SendGrid: No.AgentMail: No.
| Service | Answer |
|---|---|
| Nitrosend | Yes. Yes. Brand Kit scans your site, and AI Memory keeps house style. |
| Resend | Not a yes or no. Its AI features list URL and brand analysis, which its docs do not describe yet. |
| Brevo | Yes. Yes. The brand library fetches logo, colors, fonts and links from a URL, not tone of voice. |
| MailerSend | No. No. Templates are built in its editors. |
| Mailgun | No. No. Templates are built in its builder or in HTML. |
| SES | No. No. Templates are HTML you write. |
| Postmark | No. No. A template library you edit into your own brand. |
| Mailjet | Yes. Yes. Brand Kit suggests colors and themes from a URL, applied on paid plans, not voice. |
| SendGrid | No. No. Templates and a design editor, but you supply the design. |
| AgentMail | No. No template or brand features are documented. |
Inbound emailCan it receive and parse email sent to your domain?Nitrosend: Not a yes or no.Resend: Yes.Brevo: Yes.MailerSend: Yes.Mailgun: Yes.SES: Yes.Postmark: Yes.Mailjet: Not a yes or no.SendGrid: Yes.AgentMail: Yes.
| Service | Answer |
|---|---|
| Nitrosend | Not a yes or no. An agent inbox on your own domain, enabled by request. |
| Resend | Yes. Yes, on every plan. |
| Brevo | Yes. Yes. Inbound parsing posts replies to your webhook as JSON. |
| MailerSend | Yes. Yes, through inbound routing. |
| Mailgun | Yes. Yes, through inbound routes. |
| SES | Yes. Yes. SES receives mail through receipt rules and Mail Manager. |
| Postmark | Yes. Yes, with inbound processing on Pro and Platform. |
| Mailjet | Not a yes or no. The Parse API handles inbound, but only on Premium 50k and above. |
| SendGrid | Yes. Yes, with Inbound Parse. |
| AgentMail | Yes. Yes. Receiving, threading and replies are the core of the product, over webhooks, WebSockets or IMAP. |
Yes answersOut of the questions that have a yes or no for that service6 of 6 yes for Nitrosend4 of 5 yes for Resend5 of 6 yes for Brevo4 of 7 yes for MailerSend3 of 7 yes for Mailgun1 of 6 yes for SES3 of 6 yes for Postmark2 of 5 yes for Mailjet1 of 6 yes for SendGrid4 of 6 yes for AgentMail
At a glance
10 services, the same 7 tests, 100 points in all. In order: Nitrosend 83.75, Resend 77.5, Brevo 70, MailerSend 68.5, Mailgun 67.5, SES 65.5, Postmark 64.5, Mailjet 62.5, SendGrid 59.5, AgentMail 54. Nitrosend has the best score on Works from your AI assistant, Receipts and newsletters on one plan, Emails in your brand, no designer and Developer tools. Every price and feature was read on each company's own pages on September 26, 2026.
When another service is the better pick
Nitrosend does not win every test. Read these before you choose it.
- Pick Brevo if the most free email a month is what you need. It scores a 9 on free plan, with 300 emails a day, about 9,000 a month, transactional email included and no expiry, against Nitrosend's 7. Brevo's pricing FAQ says sending starts once Brevo approves the account.
- Pick Resend if you want an SMTP relay or inbound email on a free plan. Resend's free plan is 3,000 emails a month, capped at 100 a day, with official SDKs across languages, an SMTP relay, inbound email and React Email. A person verifies a domain before the first send. See Nitrosend and Resend compared.
- Pick Mailjet if you want a steady free allowance with SMTP. Mailjet's free plan gives 6,000 emails a month, at most 200 a day, with the APIs and SMTP relay included and no card.
- Pick Mailgun if your app receives email too. Mailgun's free plan is 100 emails a day with an inbound route, which parses incoming mail and passes it to your application. See Nitrosend and Mailgun compared.
- Pick MailerSend if you want the cheapest first paid step. MailerSend's free plan is 500 emails a month with the API and SMTP relay, and a card is required. Its Hobby plan starts at $7 a month.
- Pick Postmark if you are testing for a transactional-only product. Postmark's free Developer plan is 100 emails a month that, in its own words, never expires or runs out, and it scores a 9 on track record. See Nitrosend and Postmark compared.
- Pick AgentMail if your agent needs its own inbox. AgentMail's free plan gives 3 inboxes and 3,000 emails a month, 100 a day, with no card, and an agent can sign itself up over the API.
- Pick Amazon SES or SendGrid only if you are already on AWS or Twilio. Amazon SES offers new AWS customers up to $200 in credits rather than a free plan. SendGrid offers a 60-day trial at 100 emails a day rather than a free plan. See Nitrosend and Amazon SES compared and Nitrosend and SendGrid compared.
What each one costs once you pay
A free plan is where you start, and the price after it is where you stay. These are the list prices at 20,000 and 1,000,000 emails a month, the same two volumes used on every ranked page on this site. Amazon SES is metered, at $0.10 per 1,000 a la carte or $0.16 per 1,000 on the Essentials plan that new accounts start on from July 21, 2026.
What sending costs
List prices, USD, monthly, September 26, 2026| Service | 20,000 emails a month | 1,000,000 emails a month |
|---|---|---|
| Nitrosend (pricing page) | $20Pro, contacts unlimited | $650Scale, contacts unlimited, including overage |
| Resend (pricing page) | $20Pro, which covers 50,000 | $650Scale |
| Brevo (pricing page) | $69Standard, the first plan with automation. Starter is $32 without it | $999Professional. Standard stops at 500,000 emails |
| MailerSend (pricing page) | $35Starter, the first plan with 50 webhooks and 250 templates. Hobby with overage is $29.50 but has 1 webhook and 10 templates | $600Starter |
| Mailgun (pricing page) | $33Basic, 10,000 included and $1.80 per 1,000 after | $700Scale |
| SES (pricing page) | $3.20Lowest. Essentials, the default for a new account, or $2 a la carte. Charged per email | $160Lowest. Essentials, the default for a new account, or $100 a la carte. Charged per email |
| Postmark (pricing page) | $29.50Pro, 10,000 included and $1.30 per 1,000 after. Basic is $33 | $775Basic, the 1,500,000 plan. Pro is $852.50 |
| Mailjet (pricing page) | $41.90Premium 15,000 at $29, and $2.58 per 1,000 after. Premium 50,000 is $59, Essential has no automations | $1,099Premium 500,000 at $499, and $1.20 per 1,000 after, or a custom quote |
| SendGrid (pricing page) | $19.95Essentials, which covers 50,000 | $799Pro, the 1,500,000 plan. The 700,000 plan is $499 |
| AgentMail (pricing page) | $40Developer, 10,000 included and $2 per 1,000 extra as an add-on. Startup is $200 | Ask salesNot self-serve. Startup is capped at 150,000 a month |
At 20,000 emails a month, Nitrosend is $20, the same as Resend and a nickel more than SendGrid at $19.95. Postmark is $29.50, Mailgun $33, MailerSend $35, AgentMail $40, Mailjet $41.90 on Premium and Brevo $69 on Standard. Mailjet and Brevo are priced at their first plan with automated emails, the fair comparison with Nitrosend's $20 (Mailjet Essential is $19 for 15,000 and Brevo Starter $32, both without them).
At a million emails a month, Nitrosend is $650. MailerSend is $600, Resend $650, Mailgun $700, Postmark $775, SendGrid $799, Brevo $999 and Mailjet $1,099. AgentMail sends that volume only on a sales plan. With Amazon SES the templates, unsubscribe handling and reporting are yours to build.
Nitrosend's free and paid plans carry the same tools, so nothing is switched on when you start paying: the same API, MCP server and CLI, with campaigns and flows on the same key. The pricing page has the plans.
How we scored
Every service gets a score out of 10 on the same seven tests used on every ranked page on this site. Each test is worth a set number of points, 100 in all. The free plan test is worth 10 of them and covers the monthly volume, the daily ceiling, any one-off starter allowance, and whether the plan lasts or ends. Working from your AI assistant is worth the most, 25 points, because that is where email is heading, and it decides whether an agent can finish a free-plan setup at all.
Each test is a question with one answer per service, checked against the service's own pages on September 26, 2026. A 10 means it does the job fully on its normal plans. A 5 means it does part of it, or only on a higher plan or in a second product.
Works from your AI assistant, 25 points. Can an agent inside Claude, ChatGPT, Cursor or Codex go from nothing to a delivered transactional email, and then read back what happened to it, with no person opening the web app along the way? Scored on the first-party MCP server and what its tools cover, a CLI that works in a non-interactive runner, account and sender setup over the API, and listings in the chat apps people already work in. Scored on one written rule for every vendor: a first-party server the vendor runs and that can send counts fully; a third-party wrapper (Zapier, Composio, Kanopi, community servers) counts for less; a server that only drafts or reads counts for less than one that sends.
Receipts and newsletters on one plan, 15 points. Can receipts and password resets, and the newsletters and automated flows that follow them, go out from one account, on one bill, through one API, with the two streams kept apart?
Emails in your brand, no designer, 10 points. Does the product produce the receipt, reset and welcome emails in your brand's own logo, colors, fonts and voice, or does a developer have to write or buy the HTML template first?
Free plan, 10 points. How far can a developer get on the free plan before paying: the monthly volume, the daily ceiling, any one-off starter allowance, and whether the plan is perpetual or a trial that ends.
Price, 15 points. What does sending cost at 20,000 emails a month, where most teams start, and at 1,000,000, where a busy product ends up? Scored on list prices in US dollars, paid monthly, at the cheapest plan that covers the volume. Every ranking on this site uses the same fixed scale. At 20,000 emails, $20 or less scores 10, then $25 scores 9, $32 scores 8, $40 scores 7, $50 scores 6, $70 scores 5, $100 scores 4 and $140 scores 3. At 1,000,000, $500 or less scores 10, then $625, $800, $1,000, $1,250, $1,750, $2,500 and $3,500 step down the same way. Anything dearer, or a price given only by quote, scores 2. The score is the average of the two.
Developer tools, 15 points. How complete is what a developer builds on: a REST API with an OpenAPI spec, official SDKs across languages, a CLI, an SMTP relay, documented delivery-event webhooks, idempotent sends, a test or sandbox mode, inbound email handling, and how deep the reference docs go?
Track record and support, 10 points. How long has it run transactional sending at scale, which deliverability controls can you own (dedicated IPs, suppression, separate streams, a published uptime SLA), and what support comes with the plan?
One thing is not scored: inbox placement. No free plan here is a fair test of it, because until your own domain is verified you are measuring a shared reputation you do not control.
A free plan has two jobs, and they want different shapes
A free email API has to survive two different workloads, and only one of them is on the pricing page. The first is the build, the burst of real sends it takes to get an integration working. The second is the run, whatever your product sends afterwards, month after month.
The run is steady. Your product sends receipts, password resets and digests, which is transactional email, at whatever rate your users set off, and a monthly or daily allowance that refills is exactly the right shape for it. Every free plan on this page is shaped for the run.
The build is one burst, and an agent makes it bigger. When an assistant writes the integration, every redraft it tries is a real send, and so is each test that went to the wrong address and each retry after a timeout. All of it lands inside one afternoon, and test mail is not free mail: Resend's testing guide says test emails count against your account's sending quota.
That is why a daily cap now reads differently from a monthly one. A hundred a day is comfortable for a product that is live and sending a hundred a day. It is a hard stop for a build that wants sixty test sends in twenty minutes, then a template change, then sixty more. Resend caps the day at 100 on top of its 3,000 a month. Mailgun's free plan is 100 a day. SendGrid's trial is 100 a day. AgentMail is 100 a day. Amazon SES holds a sandboxed account to 200 messages per 24 hours. None of those is stingy. They are metered for the wrong phase.
Nitrosend's free plan is read the same way. The 5,000 is a one-off starter budget with no expiry, sized for the build, and the 500 a month is the recurring allowance, sized for the run. The daily line is separate from both: 100 recipients per rolling 24 hours on Probation, 500 on Standard and 5,000 on Trusted, pooled across the account's brands. So the fair comparison is 100 against 100. What differs is that the burst does not eat the monthly allowance, and that the daily line rises on delivery record rather than on payment.
So count the sends your integration will make before it works, not the sends your product will make once it does, and read the daily line rather than the monthly one. That is the number that decides whether you finish in one sitting.
The step that stops an agent is not the allowance
Run these free plans end to end and the allowance is rarely what you hit first. What you hit is a step in the middle that only a person can complete.
Amazon SES starts every account in a sandbox, and leaving it takes a production-access request that AWS Support reviews, with a first response within 24 hours. Brevo's pricing FAQ, read on October 1, 2026, says: "Once we approve your account for sending, you can start sending up to 300 emails per day." Resend's documentation is just as direct: "Resend sends emails using a domain you own (i.e., not a shared or public domain). You must add and verify at least one domain." A registrar login is not something an agent has. None of this is unreasonable. All of it is a person standing between the API key and the first delivered message.
Each of those steps is an abuse control, and the providers say so. AWS puts new accounts in the sandbox, in its own words, "to help prevent fraud and abuse". MailerSend's pricing FAQ says it asks for a card on the free plan "to prevent abuse of the platform". A free account is the cheapest place to try abuse, so every provider gates it. The question for an agent is what kind. A card, an approval queue and a DNS record all need a person. A sending limit that rises with delivery record is a gate an agent can pass by sending well. Nitrosend uses that kind: a new account starts at 100 recipients a day on Probation, a new sender still gets a safety review on its first send, and its pricing docs state that "payment alone does not earn trust".
The state in the middle also looks like success. A verified domain only means the DNS records are valid, not that the account is allowed to send right now. A person reads a green tick and stays suspicious. An agent reads a 200 from a verify endpoint and tells you your email is set up.
Nitrosend publishes the whole path as HTTP rather than a signup form. Its SKILL.md has a section for coding agents that can call HTTP and nothing else:
- Create the account.
POST /v1/signup, then mint a key with the token it returns. - Activate the reserved sender.
POST /v1/my/brands/{sid}/prepare_sendingreserves a name for your brand on a nitrosend.net subdomain under a root Nitrosend has already verified, with no DNS, no DKIM and no card, because a $0 plan activates without one. - Send.
POST /v1/my/messageswith anIdempotency-Keyheader, so a retry after a timeout cannot become a second email.
The same account is then reachable from the MCP server and from the command line. AgentMail has noticed the same problem. Its agent sign-up endpoint returns an API key and an inbox with no console visit, on a domain it already owns, and sends a six-digit code to a person's email address. Until that code goes back through the verify endpoint, the inbox can only send to an allowlist. Resend has some of the strongest agent tooling in the category, on the far side of a domain you verify first. Best email API for AI agents ranks the wider field on that question.
None of that is a free pass on volume or on reputation. Sending capacity is counted apart from email credits. A sender that needs no DNS is, by definition, on someone else's domain, so it shares that domain's reputation with every other account on it. Amazon built tenant management into SES for exactly this, so platforms can keep "separate reputation profiles and prevent issues with one tenant from affecting others". Ask any free plan how it keeps a stranger's spam off your sends. Nitrosend's reserved sender sits under its own shared root, and a domain you verify yourself keeps reputation and capacity separate, which is when deliverability is worth judging. The point of the reserved sender is that the first send does not wait on DNS. The email deliverability guide covers the rest.
What is not on this list, and why
- Courier. Its free Developer plan is 10,000 sends a month, which would be the largest here. Its own documentation describes it as sending "through the notification providers you already use", so the email underneath still uses somebody else's allowance or bill.
- Mailtrap. Its free sending plan is 4,000 emails a month, at most 150 a day, shared between sending and receiving. It is best known for its testing sandbox, so it is scored on Mailtrap alternatives and with email testing tools rather than here.
- Self-hosted tools such as Listmonk and Postal. Free to license and not free to run. The cost moves to a server, an IP with no reputation, and the person who keeps both alive.
Free email API FAQ
Nitrosend, with the top score in this review, 83.75 out of 100. Its free plan gives 5,000 emails to start and then 500 a month, with no card, and it is the only one here where an AI assistant can sign up, get a ready sender and send without anyone opening a dashboard. Pick Brevo if the most free email a month is what matters.
Brevo, at 300 a day and about 9,000 a month. Nitrosend's 5,000 comes up front, then 500 a month. Mailjet gives 6,000 a month with a 200 a day ceiling, and Resend and AgentMail give 3,000 a month capped at 100 a day.
Yes. Nitrosend, Brevo, Mailjet, Postmark and AgentMail say so on their own pages. MailerSend's free plan asks for a card. SendGrid's offer is a 60-day trial, and Amazon SES has no free plan, only up to $200 in AWS credits for new customers.
Partly, and only on two of the ten. Nitrosend publishes account creation at POST /v1/signup and a ready sender that needs no DNS, so the whole path is a few HTTP calls. AgentMail publishes an agent sign-up endpoint and puts inboxes on its own domain, with a one-time code to a person to unlock sending to anyone else. Everywhere else there is a DNS record at a registrar, an approval queue or a support ticket.
MailerSend has the cheapest first step at $7. At 20,000 emails a month Nitrosend and Resend are $20 and SendGrid $19.95. At a million, Nitrosend is $650 and other providers can cost less. The table above has every price.
Nitrosend, with 9 out of 10 on working from your AI assistant, the test worth the most points here. Its official MCP server, account sign-up over the API and a ready sender let an agent in Claude, ChatGPT, Cursor or Codex send with no dashboard. Resend, AgentMail and MailerSend score 8. Resend and MailerSend run hosted MCP servers, but a person creates the account first, and on Resend verifies a domain. AgentMail lets an agent sign itself up, but a person enters a one-time code before it can email anyone else.
Connect Nitrosend's MCP server. In Claude Code, run claude mcp add --transport http nitrosend https://api.nitrosend.com/mcp, then run /mcp and sign in. In Claude Desktop or claude.ai, connect Nitrosend from the connectors directory. Signing in creates the free account, with no card and no API key to paste. Then ask Claude to set up your Brand Kit from your website and send you a test email. It switches on the sender reserved for your brand on a nitrosend.net subdomain, so there is no DNS to add first. A receipt or password reset goes out as soon as it is sent, and campaigns and flows stay drafts until approved.
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