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Sendmux
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Sendmux

An Email API built specifically for AI agents, offering agent inboxes, outbound routing via user-designated providers, and automatic failover through a unified API surface.

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Rating
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Upvotes
2 months ago
Listed
Email
Email API
AI Agents
Agent Inbox
SMTP
HTTP API
Webhooks
Server-Sent Events
Outbound Routing
Tool information
Provider
Sendmux
Platforms
Web
Languages
English
API Available
Yes
Added to directory
2 months ago
Last updated
about 2 months ago
Rating
Not available
Pricing
Contact

About Sendmux

What the tool does and who it's for

Sendmux is an Email API built for AI agents that simplifies outbound mailing, agent mailboxes, routing control, and delivery events through a unified API surface. It allows users to create agent-shaped mailboxes on verified or shared domains and break free from provider lock-ins by sending from a mailbox over HTTP or SMTP protocols. Sendmux manages technical delivery friction like stripping signatures and quoted histories, handling safe HTTP retries via Idempotency-Key support, and implementing control measures such as provider weights and quotas. It also eliminates the need for polling loops through the use of signed webhooks for server delivery, an SSE stream for real-time mailbox clients, and typed change polling when clients need to resync state.

Key capabilities

Unified API surface for managing outbound emails, agent mailboxes, routing control, and delivery events.
Creation of agent-shaped mailboxes either on verified domains or shared agent-specific domains.
Freedom from provider lock-ins by enabling email sending from a mailbox over HTTP or SMTP protocols.
Automatic extraction of raw message contents, including stripping signatures and quoted history.
Optional extraction of links, headers, and attachments from incoming agent emails.
Safe HTTP retries built-in through full Idempotency-Key support.
Advanced message routing control by binding a mailbox key to active providers, selected providers, or delivery groups.
Traffic management tools, including provider weights and quotas to distribute outbound volume.
Elimination of polling loops using signed webhooks for server delivery and an SSE (Server-Sent Events) stream for real-time clients.
Typed change polling support for when a mailbox client needs to efficiently resync its state.

Pricing

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  • Full Email API access built for AI agents
  • Agent-shaped mailboxes on verified or shared domains
  • HTTP & SMTP outbound sending
  • Idempotency-Key support for safe retries
  • Provider weights and quotas traffic management
  • Signed webhooks and SSE stream real-time updates

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