letter.ai is early-stage for AEO readiness, with an overall score of 33/100 and multiple foundational gaps that limit machine interpretation. Critical discovery and indexing signals are missing, including `llms.txt` (0), schema coverage depth (0), and RSS/Atom feed (0). Content quantity is strong in places, with 29 quantitative data points (fact density score: 8) and 59 internal links (internal linking score: 7), but extractability and trust signals are weakened by missing structured data, no explicit freshness metadata, and weak entity reinforcement. In short, the site has usable content volume but lacks the technical packaging AI systems rely on for confident retrieval and citation.