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Sendmux.ai

Email inbox API for AI agents. Create agent mailboxes, receive live inbox events, and send through Gmail, Outlook, SMTP, or managed Amazon SES with quotas and failover.

Sendmux is the email inbox API for AI agents. Give an agent its own mailbox, then let it receive email, read threads, inspect attachments, send replies, and react to new messages as they arrive. Each mailbox can return cleaned message content for agents, raw email when needed, signed webhooks, and Server-Sent Events for live inbox updates.

Here’s where it helps: teams can use Sendmux for both inbound agent mailboxes and outbound email sending. Connect Gmail OAuth, Outlook OAuth, SMTP providers, or managed Amazon SES, then route mail through delivery groups with weighted routing, sender-domain routing, provider health checks, automatic failover, and quotas from per second to per day. That gives builders more control than a single-provider sending setup.

For inbound workflows, Sendmux supports custom domains with SPF, DKIM, and DMARC, mailbox-scoped API keys, sender filters, folders, labels, attachments, raw .eml downloads, IMAP retrieval, and SMTP submission. Agents can watch inbox activity through SSE, receive webhook events, or query messages and threads through the Mailbox API.

Developers can work with the Sending API, Mailbox API, Management API, OpenAPI docs, SDKs for TypeScript, Python, Go, PHP, and Ruby, the sendmux CLI, or MCP tools. Teams also get tenant isolation, provider setup, domains, logs, metrics, billing, usage tracking, and delivery history in one place.

Sendmux fits AI agent products, automation agencies, support agents, scheduling agents, ops workflows, platform builders, and controlled BYO-provider cold email setups that want to send from AI tools. Pricing is usage-based, with no per-seat fees, no per-mailbox fees, and standard email priced at $0.15 per 1,000 messages.

A startup from Melbourne, Australia that is founded by Roshan Jonnalagadda.

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Pricing:

Freemium
$0.15 (per 1000 emails)
Official Pricing

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Sendmux.ai Reviews and Details

This page is designed to help you find out whether Sendmux.ai is good and if it is the right choice for you.

#Developer Tools #Email #Email API #Email Automation #AI Agents #AI #AI Tools

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2026-06-26

Features & Specs

Email Inbox API for AI Agents

Give AI agents a real inbox to receive, read, reply to, and act on email.
Dedicated Agent Mailboxes

Create isolated mailboxes for each agent, customer, workspace, or workflow.
Mailbox History for Agent Memory

Let agents retrieve mailbox-scoped threads, messages, attachments, and past context.
Multi-Provider Email Sending

Send through Gmail OAuth, Outlook OAuth, SMTP providers, or managed Amazon SES.
Managed Amazon SES Sending

Use Sendmux-managed Amazon SES when you do not want to bring your own provider.
Per-Provider Quotas and Throttling

Set sending limits per provider by second, minute, hour, and day.
Weighted Routing and Failover

Route email across healthy providers with weighted delivery and automatic failover.
Signed Webhooks and SSE Events

Receive verified webhook events or stream live inbox updates with Server-Sent Events.
Skills, MCP, SDKs, and CLI

Give agents installable Sendmux Skills plus MCP, SDKs, and CLI access for mailbox, sending, management, and setup workflows.
Usage-Based Pricing, No Mailbox Fees

Pay for email usage and storage, with no per-seat or per-mailbox fees.

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Questions & Answers

As answered by people managing Sendmux.ai.

Which are the primary technologies used for building Sendmux.ai?

Publicly, Sendmux is built around REST and OpenAPI APIs, SMTP, IMAP, signed webhooks, Server-Sent Events, Model Context Protocol, SDKs for TypeScript, Python, Go, PHP, and Ruby, the sendmux CLI, and installable Sendmux Skills for agent workflows.
What makes Sendmux.ai unique?

Sendmux combines an email inbox API for AI agents with multi-provider outbound sending. Agents get dedicated mailboxes, mailbox-scoped API keys, cleaned message content, threads, attachments, signed webhooks, SSE live inbox events, and sending through Gmail OAuth, Outlook OAuth, SMTP, or managed Amazon SES with quotas, weighted routing, and failover.
Why should a person choose Sendmux.ai over its competitors?

Choose Sendmux if you need both inbound agent mailboxes and outbound provider control. Sending-only APIs do not give agents a real inbox, and mailbox-first tools usually do not offer bring-your-own-provider routing, per-provider quotas, and failover. Sendmux gives teams one control plane for inboxes, sending, events, providers, logs, domains, billing, MCP, SDKs, Skills, and CLI access.
How would you describe the primary audience of Sendmux.ai?

Sendmux is built for AI agent product teams, automation agencies, and platform builders that need agents to send, receive, route, and react to email in production. It also fits teams using their own Gmail, Outlook, or SMTP providers for controlled outbound and cold email workflows from AI tools.
What's the story behind Sendmux.ai?

Sendmux came from a simple problem: production AI agents need real email, not a hacked shared inbox. Teams were stitching together sending providers, mailboxes, parsers, webhook services, routing logic, and billing. Sendmux puts agent email identity, inbound mail, outbound sending, live events, and provider control into one API-first platform.
Who are some of the biggest customers of Sendmux.ai?

Target Markets, CFC, Aurora Capital

Videos

Email Inbox API for AI Agents: Inboxes, Sending, SSE, MCP

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Is Sendmux.ai good?

Sendmux.ai appears to be a solid AI-powered email and outreach automation platform that can help businesses streamline communication and scale their campaigns, though prospective users should verify current features, pricing, and reviews directly as offerings may change.

Why choose Sendmux.ai?

Leverages AI to automate and optimize email outreach, saving time on manual tasks
Aims to improve deliverability and engagement through smart sending strategies
Can help scale cold email and marketing campaigns efficiently
Potentially useful for personalizing messages at volume
May offer analytics to track campaign performance and refine outreach

Recommended for

Sales teams running cold email and outreach campaigns
Startups and small businesses looking to scale email marketing affordably
Marketing agencies managing multiple client campaigns
Growth-focused teams wanting AI-driven automation for lead generation
Solo founders seeking to automate prospecting without a large team

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Is Sendmux.ai good? This is an informative page that will help you find out. Moreover, you can review and discuss Sendmux.ai here. The primary details have been verified within the last quarter. So they could be considered up to date. If you think we are missing something, please use the means on this page to comment or suggest changes. All reviews and comments are highly encouranged and appreciated as they help everyone in the community to make an informed choice. Please always be kind and objective when evaluating a product and sharing your opinion.

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