sendmux

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1. 9/14/2026

   Updated: best for, features, limitations, summary, use cases, walkthrough

   See recorded changes

   bestFor

   Before: ["Teams and developers building AI agents that require integrated email sending and receiving capabilities with flexible provider routing."]

   After: ["AI developers needing integrated email inboxes and sending capabilities for their agents.","Teams requiring multi-tenant email management with usage-based billing and provider flexibility."]

   features

   Before: ["Create agent inboxes with real email addresses on real domains.","Inbound mailboxes return parsed clean JSON with stripped signatures, quoted history, and tracking pixels to save LLM tokens.","Outbound sending supports routing through multiple connected providers with weighted distribution and automatic failover on failure.","Supports multiple access surfaces including REST, SSE, IMAP, SMTP, and signed webhooks for mailbox events.","Automatic email thread grouping by Message-ID and References headers compliant with RFC 2822."]

   After: ["Create agent inboxes with real email addresses on real domains.","Outbound email routing through multiple connected providers with weighted distribution and automatic failover.","Inbound mailboxes return parsed clean JSON with stripped signatures, quoted history, and extracted links to save LLM tokens.","Supports multiple access methods including REST API, Server-Sent Events (SSE), IMAP, SMTP, and signed webhooks for inbound mail.","Automatic email thread grouping by Message-ID and References headers compliant with RFC 2822."]

   limitations

   Before: ["Free plan limits to two mailboxes and 50 accepted recipients daily across all outbound routes with fixed usage credit and no top-ups.","Managed sending has fair usage and operational safety limits with higher daily limits available only by review on Pro plans."]

   After: ["Free plan limits to two mailboxes and 50 accepted recipients daily across all outbound routes with fixed usage credit.","Higher managed daily sending limits are only available by review and not included in Free or Pro plans by default."]

   summary

   Before: "Sendmux is an email API designed for AI agents that provides real inboxes for sending and receiving emails through user-owned providers with automatic failover. It offers a unified API for outbound sending and inbound mailboxes, delivering clean JSON instead of raw HTML, and supports multi-tenant team environments with scoped API keys and usage-based billing."

   After: "Sendmux is an email API designed for AI agents, providing real inboxes for sending and receiving emails through user-owned providers with automatic failover. It offers clean JSON parsing of inbound emails, multi-provider outbound routing, and tenant isolation for teams."

   useCases

   Before: ["Manage transactional and conversational email flows with provider failover and quota enforcement."]

   After: ["Enable AI agents to send and receive emails with real inboxes and clean parsed content for efficient processing.","Manage multi-tenant email infrastructure for teams with isolated providers, mailboxes, API keys, and metrics."]

   walkthrough

   Before: []

   After: ["Create a mailbox using the management API with a JSON body specifying the email address.","Stream incoming mailbox events over server-sent events (SSE) to receive new messages in real time."]