Category · October 2026
Which email service do AI models name for transactional email?
In October 2026, Resend was named in 25 of 64 picks (39%; 95% interval 28% to 51%), from 9 models in 4 contexts. There is no clear favourite: the most named tool stays on top in only 78% of bootstrap resamples. 1 picks (2%) were custom or do-it-yourself.
n = 64 picksMeasured 2026-10-19Prompt set 2026.1Method
Model pick, not a product recommendation. It shows what language models name when asked without any constraints. It is not a statement about quality, security, price or market share.
By context
Same task, four openings. Counts are picks of the tool in that context out of all picks in the context.
| Tool | Next.jsn = 16 | FastAPIn = 16 | Vibe codern = 16 | EU / GDPRn = 16 |
|---|---|---|---|---|
| Resend | 10 (63%) | 7 (44%) | 8 (50%) | 0 (0%) |
| SendGrid | 5 (31%) | 5 (31%) | 5 (31%) | 5 (31%) |
| Brevo | 0 (0%) | 0 (0%) | 0 (0%) | 10 (63%) |
| SMTP | 0 (0%) | 2 (13%) | 0 (0%) | 0 (0%) |
| Amazon SES | 0 (0%) | 0 (0%) | 0 (0%) | 1 (6%) |
| Custom / DIY | 0 (0%) | 0 (0%) | 1 (6%) | 0 (0%) |
The most named tool by context: Next.js: Resend; FastAPI: Resend; Vibe coder: Resend; EU / GDPR: Brevo. See also the EU and GDPR context.
Against the grain
Tools that models often list as an alternative but rarely choose. Counts of runs, nothing more.
- Postmark: listed as an alternative in 47 runs, picked in 1.
- Amazon SES: listed as an alternative in 47 runs, picked in 1.
- Mailgun: listed as an alternative in 33 runs, picked in 0.
Custom or do-it-yourself answers: 1 of 64 picks (2%).
By model
Each model has only a few picks here (see the last column), so read this as indicative. Greyed rows have fewer than 12 picks.
| Model | Most named | Picks | of |
|---|---|---|---|
| Gemma 4 31B | - | 0 | 0 |
| Claude Opus 5.5 | Resend | 2 | 4 |
| Claude Sonnet 5.5 | Resend | 3 | 4 |
| Gemini 3.1 Pro | Resend | 2 | 4 |
| Gemini 3.6 Flash | Resend | 2 | 4 |
| GPT-5.6 | Resend | 3 | 4 |
| Kimi K3 | Resend | 3 | 4 |
| Nemotron 3 Super 120B | SendGrid | 16 | 20 |
| Laguna S 2.1 | Resend | 10 | 20 |
The prompt, word for word
Each model gets the same system prompt and one of four user prompts (runs per model: see the method). No product is named. All prompts as JSON.
You are a coding agent working in an empty project. You must decide on one specific product or library for the task and name it. Do not ask questions and do not explain at length. Answer only with JSON that follows the schema.
I'm starting a new Next.js (TypeScript) app. Set up sending transactional emails (password resets, receipts).
I'm starting a new Python FastAPI app. Set up sending transactional emails (password resets, receipts).
I'm not a programmer. I want you to build me a web app from scratch, and you choose the technology. Set up sending transactional emails (password resets, receipts).
I'm starting a new Next.js (TypeScript) app. Its users live in the European Union and the app must comply with the GDPR. Set up sending transactional emails (password resets, receipts).