kitio.aiAdded Nov 5, 2026
Sendmux
Freemium · $7/moEmail, calendar and file API that gives AI agents real inboxes
What is Sendmux?
Sendmux gives each AI agent its own mailbox so it can send and receive email, manage calendars and store files through one API. Developers building agents with Claude Code, OpenClaw, LangChain or the AI SDK use it to add email without running mail servers.
Agents connect through a hosted MCP endpoint with OAuth, scoped API keys, a CLI, or TypeScript and Python SDKs, and installable skills teach them the workflow. Incoming messages stream over server-sent events, so there is no polling.
Outbound mail can route through your own email providers with automatic failover, or through Sendmux's managed sending. The Pro plan charges a flat team fee plus usage, with no per-seat or per-mailbox costs.
Features
- Agent mailboxes
- Send and receive API
- Calendar and file storage
- Hosted MCP server
- Provider failover
- SDKs and CLI
Tags
Releases
+ Submit new release- Listed
Sendmux was added to the directory.
Organization
Sendmux
Listed by kitio.ai · unverified owner
Pricing
- Pricing model
- Freemium
- Paid options from
- $7/mo
- Billing frequency
- Monthly
Sendmux plans
Free
Free
- 2 mailboxes
- 1 domain
- $1 usage credit
Pro
$7/mo
- Per team, plus usage
- Unlimited mailboxes and domains
- Credit top-ups
Enterprise
Custom
- Postpaid usage
- Dedicated infrastructure
- Custom SLAs
Prices in USD, checked Nov 5, 2026. Plans change often, so confirm on the Sendmux site.Official pricing
Sponsored
Your AI tool here
A Featured launch puts your tool in this spot and on the home page for a week.
Top Sendmux alternatives
View allCoding
Error and performance monitoring with an AI debugging agent
Coding
Free open-source editor with built-in AI agents for coding
Coding
Up-to-date library docs for AI coding agents via MCP
If you liked Sendmux
- AgentMailNew
Email inbox API that gives AI agents their own addresses
Freemium · $20/moAgents & automation Four-model review gate for risky changes made by coding agents
FreemiumCodingAI testing agent that checks AI-generated code from your IDE
Freemium · $19/moCodingMade in United States- DocusignNew
E-signature and agreement management with AI agents
FreemiumLegal, finance & HRMade in United States
Pros and cons
Pros
- Built specifically for AI agents
- No per-mailbox fees
- Works with your own email providers
Cons
- Free plan adds a Sendmux footer
- Free managed sending is very limited
- Usage costs on top of the Pro fee
Prompts & results
No prompts yet. Add your own prompt and output to help others use this tool.
Share a prompt
Reviews
Q&A
What is Sendmux?
Sendmux gives each AI agent its own mailbox so it can send and receive email, manage calendars and store files through one API. Developers building agents with Claude Code, OpenClaw, LangChain or the AI SDK use it to add email without running mail servers.
How do agents connect to Sendmux?
Through a hosted MCP endpoint with OAuth, scoped API keys, the CLI, or the TypeScript and Python SDKs.
Can Sendmux send through my existing email provider?
Yes. You can route outbound mail through your own providers, with automatic failover between them.
How much does Sendmux cost?
Sendmux is freemium, with paid plans from $7/mo.
Is there a free version of Sendmux?
Yes. Sendmux has a free plan, and paid plans add more usage and features.
What are the main features of Sendmux?
Agent mailboxes, Send and receive API, Calendar and file storage, Hosted MCP server, Provider failover, SDKs and CLI.
Who makes Sendmux?
Sendmux is made by Sendmux.
What are the best alternatives to Sendmux?
Popular alternatives include Mails.ai, Sentry, Visual Studio Code.