Who builds Mailbay

Who I am#

I'm Arin Prajapati, a software engineer in Mumbai, India. I write JavaScript and TypeScript, Python, Go and Java, and most of my work is AI automation and data pipelines: programs that collect data, move it between systems and act on it without a person watching. Mailbay is the same kind of work, pointed at email.

Why Mailbay exists#

Agents and apps keep needing email. An agent signs up for a service and has to read the confirmation code. An app sends receipts and has to know they arrived. A support address needs answers from code as well as from people. The usual answers are a person's inbox shared with a script, or a sending API that resells someone else's mail servers.

Mailbay gives agents and apps their own inboxes and sending, from one API, a CLI or MCP. An agent creates an address in one call, waits for the next email and gets the code already pulled out. An app sends from a domain it owns.

It runs on its own mail servers, with no relay behind them: our SMTP server receives mail, our KumoMTA sends it from our own IP addresses, and the mail is stored on our own server. That is more work, and I wrote down why we run our own mail servers and what it costs.

It is a beta, and I try to keep it an honest one. Mailbay is free while the beta runs, the paid plans are planned and cannot be bought yet, and the changelog says what shipped and when. Every claim on this site is meant to match what the product does today. If you find one that does not, write to me and I will fix it.

Proof of work#

Before Mailbay I built Sloth, an open source tool to watch and control Claude Code and other terminal coding agents from a phone browser. Its code is public, so you can see how I work before you trust me with your mail.

Mailbay itself is ten Rust crates and a Next.js app. The architecture tour of Mailbay's Rust code walks through them, and the Mailbay blog has the rest of my notes.

Reach me#

• LinkedIn: linkedin.com/in/arin-prajapati
• GitHub: github.com/ArinPrajapati
• Email: hello@mailbay.dev for the product, privacy@mailbay.dev for privacy questions.

I run Mailbay as a sole proprietor; the legal pages have the details. If you want to try it, join the beta.