# Building with email

How email APIs compare, how to build on them, and how the parts of AI Inbx work.

-   [5 November 2026EngineeringInboxes are the wrong primitive for platformsInbox-centric email APIs suit one agent with one owner. Platforms serving customers need addresses that work without being created and a bill per email.Pau Kraft](/blog/why-inboxes-are-the-wrong-primitive)
-   [5 November 2026ComparisonsBest email APIs for cold outreach tools (2026)What a cold-outreach product needs from its email API, and how 12 providers compare on terms, send limits, sending hours, replies and per-customer separation.Pau Kraft](/blog/email-api-for-cold-outreach-tools)

-   [5 November 2026ComparisonsBest email APIs for AI agents (2026)Why I think AI Inbx is the best email API for products that give agents email, the bugs it saves you from, and when AgentMail, Nylas or Postmark fit better.Pau Kraft](/blog/best-email-api-for-ai-agents)
-   [5 November 2026ComparisonsAI Inbx vs Nylas for email in your product (2026)AI Inbx vs Nylas for Gmail and Outlook products: threads without reply headers, inline answers, out-of-office return dates, opt-outs, pacing and pricing.Pau Kraft](/blog/ai-inbx-vs-nylas)
-   [5 November 2026ComparisonsThe best AgentMail alternatives (2026)Seven AgentMail alternatives for platforms, compared on per-inbox pricing, catch-all domains, users' Gmail and Outlook, opt-out replies and outreach rules.Pau Kraft](/blog/agentmail-alternatives)
-   [5 November 2026ComparisonsAI Inbx vs AgentMail: inboxes vs addresses (2026)AgentMail bills per inbox; on AI Inbx every address works and the bill follows email. Threads, out-of-office dates, opt-outs, pacing and three worked bills.Pau Kraft](/blog/ai-inbx-vs-agentmail)
-   [5 November 2026ComparisonsThe best Nylas alternatives (2026)Aurinko, Unipile, EmailEngine and AI Inbx vs Nylas for Gmail and Outlook products: threading, reply text, out-of-office dates, opt-outs, cost per account.Pau Kraft](/blog/nylas-alternatives)

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