# Startup Mail guides

> Practical guides to custom-domain email, AI-agent mailboxes, email infrastructure, security, and operations.

## Custom-domain email

- [How to get custom-domain email without an office suite](https://staging.startupmail.dev/guides/custom-domain-email-without-office-suite.md): Set up email on your own domain without buying calendars, documents, meetings, and other office-suite tools you may not need.
- [Email forwarding vs a real mailbox](https://staging.startupmail.dev/guides/email-forwarding-vs-real-mailbox.md): Learn when custom-domain email forwarding is enough, when you need a stored mailbox, and what happens when you reply from Gmail or Outlook.
- [Email aliases vs separate mailboxes vs shared inboxes](https://staging.startupmail.dev/guides/email-alias-vs-mailbox-vs-shared-inbox.md): Choose the right setup for founder@, hello@, and support@: an alias, a separate mailbox, or an inbox shared by a team.

## AI-agent email

- [The complete guide to email for AI agents](https://staging.startupmail.dev/guides/email-for-ai-agents.md): Learn how to give an AI agent a real mailbox with scoped access, durable threads, safe sending, webhooks, MCP tools, and human review.
- [Should an AI agent use Gmail or a dedicated mailbox?](https://staging.startupmail.dev/guides/ai-agent-gmail-vs-dedicated-mailbox.md): Choose between connecting an AI agent to Gmail and giving it a dedicated mailbox by comparing identity, OAuth access, isolation, human use, and cost.
- [How to give an AI agent an email address on your domain](https://staging.startupmail.dev/guides/give-ai-agent-email-address.md): Set up a custom-domain mailbox for an AI agent with safe DNS changes, narrow permissions, MCP or webhook access, and human approval.

## Email infrastructure

- [Email API vs inbox API: What are you actually building?](https://staging.startupmail.dev/guides/email-api-vs-inbox-api.md): Learn the difference between a sending API, inbound email processing, and an inbox API, then choose the right email architecture for your product.
- [Transactional email service vs business email hosting](https://staging.startupmail.dev/guides/transactional-email-vs-business-email.md): Understand the difference between transactional email services and business email hosting, including inboxes, replies, pricing, and common use cases.
- [Inbound email webhook vs persistent mailbox: which do you need?](https://staging.startupmail.dev/guides/inbound-email-webhook-vs-persistent-mailbox.md): Compare inbound email webhooks with persistent mailboxes, including storage, threads, retries, human access, and the cases where you need both.

## Security and operations

- [How to secure an AI agent that reads email](https://staging.startupmail.dev/guides/secure-ai-agent-email.md): Build a safer email agent with a narrow threat model, mailbox-scoped access, recipient rules, stored drafts, human approval, and audit records.