# State of AI Search: Email API - October 2026

> We asked ChatGPT, Claude, Gemini, Perplexity, and Google's AI Overview 20 questions about transactional email APIs and analyzed 816 answers. Postmark leads with 84% visibility.

- **Published:** October 8, 2026
- **Assistants:** ChatGPT, Claude, Gemini, Perplexity, and Google's AI Overview
- **Coverage:** 20 prompts, 816 answers, 15 tracked brands, 554 cited domains
- **Data:** [data.csv](https://www.usenotra.com/state-of-ai-search/email-api/2026-10/data.csv?ntr=l6hJ2ifKSxhHSnw_)

## Key findings

- Postmark and Resend are neck and neck: 84% and 79% on average across the assistants.
- Resend is named first most often (39% of answers on average across the assistants), even though Postmark is mentioned more.
- Claude names 5.9 tracked brands per answer, Perplexity only 2.8.
- The assistants agree on the brand to name first for 45% of prompts.
- Google showed an AI Overview for 84% of the prompts we checked.

## Visibility ranking

Visibility is the share of answers that name the brand. Named first is the share that name it before any other tracked brand, own site cited the share that link to the brand's own domain. All three are averaged across the assistants, so each assistant counts the same however many answers it gave.

| # | Brand | Visibility | Named first | ChatGPT | Claude | Gemini | Perplexity | AI Overview | Own site cited |
| ---: | --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| 1 | [Postmark](https://postmarkapp.com) | **84%** | 23% | 87% | 100% | 90% | 71% | 75% | 31% |
| 2 | [Resend](https://resend.com) | **79%** | 39% | 85% | 94% | 98% | 61% | 56% | 29% |
| 3 | [Amazon SES](https://aws.amazon.com) | **77%** | 13% | 78% | 94% | 86% | 57% | 69% | 24% |
| 4 | [SendGrid](https://sendgrid.com) | **66%** | 11% | 58% | 87% | 72% | 44% | 69% | 9% |
| 5 | [Mailgun](https://mailgun.com) | **46%** | 4% | 44% | 68% | 54% | 20% | 44% | 10% |
| 6 | [Brevo](https://brevo.com) | **27%** | 2% | 14% | 52% | 28% | 14% | 25% | 16% |
| 7 | [Loops](https://loops.so) | **11%** | 3% | 9% | 20% | 17% | 4% | 6% | 4% |
| 8 | [Mailtrap](https://mailtrap.io) | **11%** | 1% | 0% | 43% | 8% | 6% | 0% | 14% |
| 9 | [Customer.io](https://customer.io) | **10%** | 2% | 11% | 12% | 11% | 8% | 6% | 3% |
| 10 | [MailerSend](https://mailersend.com) | **6%** | 0% | 3% | 15% | 7% | 1% | 6% | 2% |
| 11 | [SparkPost](https://sparkpost.com) | **2%** | 0% | 0% | 5% | 3% | 0% | 0% | 0% |
| 12 | [ZeptoMail](https://zeptomail.com) | **2%** | 0% | 3% | 1% | 5% | 0% | 0% | 0% |
| 13 | [Plunk](https://useplunk.com) | **1%** | 0% | 0% | 1% | 4% | 0% | 0% | 0% |
| 14 | [Bird](https://bird.com) | **1%** | 0% | 0% | 1% | 3% | 0% | 0% | 0% |
| 15 | [Mailchimp Transactional](https://mailchimp.com) | **0%** | 0% | 0% | 0% | 0% | 0% | 0% | 0% |

## By assistant

| Assistant | Model | Answers | Brands per answer | Sources per answer |
| --- | --- | ---: | ---: | ---: |
| ChatGPT | `openai/gpt-5.6-sol` | 200 | 3.9 | 17.4 |
| Claude | `anthropic/claude-opus-5.5` | 200 | 5.9 | 9.6 |
| Gemini | `google/gemini-3.8-flash` | 200 | 4.8 | 4.8 |
| Perplexity | `perplexity/sonar` | 200 | 2.8 | 15 |
| AI Overview | `google/ai-overview` | 16 | 3.6 | 6.5 |

## Prompts

The 20 questions we asked, with the brand named first most often and the others that came up.

| # | Prompt | Named first | Also named |
| ---: | --- | --- | --- |
| 1 | sendgrid alternatives with better deliverability | **SendGrid** | Postmark, Amazon SES, Mailgun, Resend, +6 more |
| 2 | best transactional email api | **Postmark** | Resend, Amazon SES, SendGrid, Mailgun, +5 more |
| 3 | best email api with react email templates | **Resend** | Postmark, Amazon SES, SendGrid, Loops, +5 more |
| 4 | i need to send receipts and notifications from my app, what service | **Resend** | Postmark, Amazon SES, SendGrid, Brevo, +5 more |
| 5 | best email api for product and marketing emails in one place | **Brevo** | Resend, Customer.io, SendGrid, Loops, +5 more |
| 6 | what should i use to send emails from my next.js app | **Resend** | Amazon SES, Postmark, SendGrid, Brevo, +4 more |
| 7 | cheapest reliable email api for a startup | **Amazon SES** | Resend, Postmark, Brevo, Mailgun, +4 more |
| 8 | which email api has the best developer experience | **Resend** | Postmark, SendGrid, Amazon SES, Mailgun, +4 more |
| 9 | best email service for saas onboarding emails | **Customer.io** | Loops, Resend, Postmark, Brevo, +4 more |
| 10 | best smtp service for a django app | **Postmark** | Amazon SES, Resend, SendGrid, Mailgun, +4 more |
| 11 | best email provider for a hobby project | **Resend** | Amazon SES, Brevo, Postmark, Mailtrap, +4 more |
| 12 | what email provider should i use for high volume transactional email | **Amazon SES** | Postmark, SendGrid, Mailgun, Resend, +3 more |
| 13 | which email api is best for deliverability to gmail | **Postmark** | Amazon SES, SendGrid, Mailgun, Resend, +3 more |
| 14 | best transactional email api with an eu data region | **Mailgun** | Amazon SES, Brevo, Postmark, Resend, +3 more |
| 15 | how do i send password reset emails from node | **SendGrid** | Postmark, Resend, Amazon SES, Mailgun, +2 more |
| 16 | what's the easiest way to send emails from a serverless function | **Resend** | Amazon SES, Postmark, SendGrid, Mailgun, +2 more |
| 17 | how do i send transactional emails from several customer domains | **Amazon SES** | Postmark, SendGrid, Mailgun, Resend, +2 more |
| 18 | i need reliable email webhooks and delivery logs, what should i use | **Postmark** | Resend, Amazon SES, Mailgun, SendGrid, +2 more |
| 19 | which email api makes bounce and complaint handling easiest | **Postmark** | Resend, Amazon SES, SendGrid, Mailgun |
| 20 | resend vs postmark vs sendgrid | **Resend** | Postmark, SendGrid, Amazon SES |

## What the assistants say

### Postmark

> Postmark is usually the strongest SendGrid alternative when transactional-email deliverability is the priority.
>
> ChatGPT, asked "sendgrid alternatives with better deliverability"

> Postmark: best when delivery has to be reliable (password resets, payments, healthcare)
>
> Claude, asked "best transactional email api"

> Postmark is slightly more expensive, but it has the best deliverability reputation in the industry.
>
> Gemini, asked "cheapest reliable email api for a startup"

### Resend

> Resend has the best developer experience overall, especially for TypeScript, Node.js, Next.js, or React applications.
>
> ChatGPT, asked "which email api has the best developer experience"

> Resend: best developer experience, good for new projects
>
> Claude, asked "best transactional email api"

> Resend has become the default choice for modern tech startups (especially those using TypeScript/React) because of its developer experience and fair pricing.
>
> Gemini, asked "cheapest reliable email api for a startup"

### Amazon SES

> Amazon SES is the cost winner. À-la-carte outbound sending is currently $0.10 per 1,000 emails.
>
> ChatGPT, asked "best transactional email api"

> Amazon SES: best if you need the lowest cost at high volume.
>
> Claude, asked "sendgrid alternatives with better deliverability"

> Amazon SES (Simple Email Service) *(Best for high volume / lowest cost)*
>
> Gemini, asked "i need to send receipts and notifications from my app, what service"

### SendGrid

> SendGrid -- best feature breadth and enterprise infrastructure, but heavier to operate.
>
> ChatGPT, asked "resend vs postmark vs sendgrid"

> SendGrid: best for large companies with marketing needs.
>
> Claude, asked "best email api with react email templates"

> SendGrid sends billions of emails per month and is the default enterprise standard.
>
> Gemini, asked "best transactional email api"

### Mailgun

> Mailgun: Good if you need email validation, routing, and sophisticated deliverability tooling, but it wouldn't be my first choice purely for straightforward transactional Gmail delivery.
>
> ChatGPT, asked "which email api is best for deliverability to gmail"

> Mailgun: best for receiving and processing incoming email.
>
> Claude, asked "best transactional email api"

> Mailgun: Best for complex inbound routing and regex parsing of incoming mail, though its dashboard and onboarding experience are noticeably clunkier than Resend's.
>
> Gemini, asked "which email api has the best developer experience"

## Cited sources

The domains the assistants link to most, by share of answers that cite them at least once, averaged across the assistants.

| # | Domain | Cited in | ChatGPT | Claude | Gemini | Perplexity | AI Overview | Top page |
| ---: | --- | ---: | ---: | ---: | ---: | ---: | ---: | --- |
| 1 | [postmarkapp.com](https://postmarkapp.com) | **31%** | 86% | 4% | 24% | 30% | 13% | [www.postmarkapp.com](https://www.postmarkapp.com/pricing) |
| 2 | [resend.com](https://resend.com) | **29%** | 80% | 0% | 17% | 42% | 6% | [Pricing - Resend](https://resend.com/pricing?contacts=100000&product=marketing) |
| 3 | [sequenzy.com](https://sequenzy.com) | **21%** | 1% | 56% | 9% | 34% | 6% | [The 24 Best Transactional Email Services in 2026 (Tested & Compared)](https://www.sequenzy.com/blog/best-transactional-email-services) |
| 4 | [docs.aws.amazon.com](https://docs.aws.amazon.com) | **17%** | 64% | 1% | 0% | 23% | 0% | [docs.aws.amazon.com](https://docs.aws.amazon.com/pdfs/ses/latest/dg/ses-dg.pdf) |
| 5 | [aws.amazon.com](https://aws.amazon.com) | **15%** | 38% | 1% | 11% | 28% | 0% | [aws.amazon.com](https://aws.amazon.com/about-aws/whats-new/2026/07/amazon-ses-pricing-plans/) |
| 6 | [brevo.com](https://brevo.com) | **14%** | 5% | 34% | 8% | 25% | 0% | [Best Email API Services 2026: 8 Providers Compared](https://www.brevo.com/blog/best-email-api/) |
| 7 | [mailtrap.io](https://mailtrap.io) | **14%** | 2% | 34% | 20% | 17% | 0% | [mailtrap.io](https://mailtrap.io/blog/transactional-email-services/) |
| 8 | [courier.com](https://courier.com) | **13%** | 3% | 17% | 13% | 25% | 6% | [courier.com](https://www.courier.com/integrations/list/transactional-email) |
| 9 | [reddit.com](https://reddit.com) | **12%** | 8% | 0% | 3% | 1% | 50% | [reddit.com](https://www.reddit.com/r/webdev/comments/1qj0m6r/who_offers_the_best_transactional_email_api_out/) |
| 10 | [twilio.com](https://twilio.com) | **12%** | 28% | 6% | 7% | 13% | 6% | [Email API Pricing \| Twilio](https://www.twilio.com/en-us/products/email-api/pricing) |

## More reports

- [AI visibility](https://www.usenotra.com/state-of-ai-search/ai-visibility/2026-10?ntr=l6hJ2ifKSxhHSnw_): Otterly.AI leads with 70%
- [App hosting](https://www.usenotra.com/state-of-ai-search/app-hosting/2026-10?ntr=l6hJ2ifKSxhHSnw_): Render leads with 73%
- [Auth](https://www.usenotra.com/state-of-ai-search/auth/2026-10?ntr=l6hJ2ifKSxhHSnw_): Clerk leads with 73%
- [Changelog](https://www.usenotra.com/state-of-ai-search/changelog/2026-10?ntr=l6hJ2ifKSxhHSnw_): Beamer leads with 54%
- [Postgres](https://www.usenotra.com/state-of-ai-search/postgres/2026-10?ntr=l6hJ2ifKSxhHSnw_): Neon leads with 88%

All reports: https://www.usenotra.com/state-of-ai-search

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