Clear guides to business and programmable email
Learn how inboxes, delivery APIs, webhooks, custom domains, and agent access fit together.
Custom-domain email
Choose addresses, mailboxes, forwarding, and the right setup for a small team.
How to get custom-domain email without an office suite
Set up email on your own domain without buying calendars, documents, meetings, and other office-suite tools you may not need.
Read guide CUSTOM-DOMAIN EMAILEmail forwarding vs a real mailbox
Learn when custom-domain email forwarding is enough, when you need a stored mailbox, and what happens when you reply from Gmail or Outlook.
Read guide CUSTOM-DOMAIN EMAILEmail aliases vs separate mailboxes vs shared inboxes
Choose the right setup for founder@, hello@, and support@: an alias, a separate mailbox, or an inbox shared by a team.
Read guideAI-agent email
Give agents durable addresses, narrow access, and a safe path to human review.
The complete guide to email for AI agents
Learn how to give an AI agent a real mailbox with scoped access, durable threads, safe sending, webhooks, MCP tools, and human review.
Read guide AGENTS / MAILBOX DESIGNShould an AI agent use Gmail or a dedicated mailbox?
Choose between connecting an AI agent to Gmail and giving it a dedicated mailbox by comparing identity, OAuth access, isolation, human use, and cost.
Read guide AGENTS / SETUP GUIDEHow to give an AI agent an email address on your domain
Set up a custom-domain mailbox for an AI agent with safe DNS changes, narrow permissions, MCP or webhook access, and human approval.
Read guideEmail infrastructure
Understand APIs, webhooks, inbox storage, threading, and transactional delivery.
Email API vs inbox API: What are you actually building?
Learn the difference between a sending API, inbound email processing, and an inbox API, then choose the right email architecture for your product.
Read guide CHOOSING EMAIL INFRASTRUCTURETransactional email service vs business email hosting
Understand the difference between transactional email services and business email hosting, including inboxes, replies, pricing, and common use cases.
Read guide DEVELOPERS / INBOUND EMAILInbound email webhook vs persistent mailbox: which do you need?
Compare inbound email webhooks with persistent mailboxes, including storage, threads, retries, human access, and the cases where you need both.
Read guideSecurity and operations
Control what automated mail systems can read, send, and do with untrusted input.