This category has the smallest source list of any we mapped, and the most obvious tactic behind it.
We ran fifteen buying questions through grounded search — the questions a real buyer types, not keywords — and recorded which tools the answers named and which sources they cited. 25 distinct sources, 137 citations. What follows is that data.
What AI models actually name
| Tool | Mentions |
|---|---|
| AgentMail | 15 |
| Amazon SES | 15 |
| Mailtrap | 15 |
| Mailgun | 14 |
| Postmark | 14 |
| Twilio SendGrid (also cited as SendGrid) | 14 |
| MailerSend | 11 |
| Mailjet | 10 |
| Brevo | 6 |
| Resend | 6 |
| Elastic Email | 3 |
| SMTP2GO | 3 |
| SMTP.com | 2 |
| Bird | 1 |
The single most-cited source here is a vendor's own comparison of itself against its competitors — and that vendor is also tied for most-named in the answers.
Look at the top sources: agentmail.to, twilio.com, mailtrap.io, mailerlite.com,
mailjet.com, postmarkapp.com. Almost every one is a company in the category publishing a
roundup that includes itself, on its own domain.
It works, and it is worth being blunt: this article is the same shape. The difference we would argue for is that a roundup should be worth citing on its merits, which is why ours is built from measurement rather than opinion. Three names tied at the top of the answers — AgentMail, Amazon SES and Mailtrap — and two of the three publish exactly this kind of page.
Where the answers come from
These are the pages the models cited most. The top three carry 31% of all citations in this category, and Reddit threads carry 20% across 7 separate discussions.
Method
Fifteen buying questions, run through grounded search on 3 September 2026:
What are the best Email APIs For Developers brands? · Which Email APIs For Developers should I buy? · Best Email APIs For Developers for beginners · Most trusted Email APIs For Developers brands and why · Compare the top Email APIs For Developers brands · What Email APIs For Developers do experts recommend? · Best value Email APIs For Developers · Which Email APIs For Developers brands have the best reviews? · Top rated Email APIs For Developers 2026 · What should I look for when choosing Email APIs For Developers? · Alternatives to the most popular Email APIs For Developers · Is there a better option than the leading Email APIs For Developers brand? · What do people on Reddit recommend for Email APIs For Developers? · Best Email APIs For Developers for small businesses · What's the highest rated Email APIs For Developers right now?
Every answer carries citations. We recorded all of them and ranked by frequency.
What this does not do. We did not test these tools, run trials, or compare features hands-on. Plenty of roundups claim they did. We measured which tools AI models recommend and which sources those recommendations came from — a different question, and the one that matters if your goal is being recommended rather than choosing.
Reproducibility. Ask the same questions again and substantially the same sources come back. In our testing, two independent runs of a category minutes apart returned the same URLs in the same order.
This is one of seven categories we mapped the same way. Across all seven, Reddit carried 16-27% of citations and the top three sources carried 29-33% — every single time.
This source map was made with Mayin.
Every number above came from running real buying questions through grounded search and recording what the answers cited. You can get the same map for your own category and brand in about 15 minutes, for $49 — one payment, no subscription, delivered in Telegram.