Unlocks exact competitor prompt citation ranks, /llms-full.txt corpus & JSON-LD entity patches
AI Search Visibility Leaderboard: Transactional Email APIs for Developers
Live 2026 AI Search Citation Share-of-Voice (cSoV) benchmark for Email Delivery APIs. Compare Resend (38.1%), Postmark (26.5%), SendGrid (19.8%), and AWS SES (15.6%) across ChatGPT Search, Perplexity, and Gemini.
Answer-First Executive Summary (Email Delivery APIs)
Across 25 unbranded commercial buyer prompts in Email Delivery APIs, Resend leads AI answer engine visibility with 38.1% weighted Citation Share-of-Voice (cSoV), followed by Postmark (26.5%), SendGrid (19.8%), and AWS SES (15.6%). Brands with a valid root /llms.txt manifest and explicit PerplexityBot + OAI-SearchBot permissions captured 2.4x more rank #1 citations.
| Rank | Brand | Domain | Weighted cSoV | /llms.txt Status | JSON-LD Score |
|---|---|---|---|---|---|
| #1 | Resend | resend.com | 38.1% | Active (/llms.txt + /llms-full.txt) | 94/100 |
| #2 | Postmark | postmark.com | 26.5% | Partial (/llms.txt only) | 84/100 |
| #3 | SendGrid | sendgrid.com | 19.8% | Missing (404) | 76/100 |
| #4 | AWS SES | awsses.com | 15.6% | Missing (404) | 68/100 |
Deploying a spec-compliant /llms.txt and SoftwareApplication + FAQPage JSON-LD graph is the highest-leverage engineering move to overtake Resend and Postmark in Email Delivery APIs prompts.
Run a Live 10-Second GEO Audit on Your Own Domain
Compare your cSoV against Resend and auto-compile your custom /llms.txt + JSON-LD graph.