# Compare email services by the job you need done > Compare Startup Mail with mailbox providers, email APIs, agent inbox platforms, and office suites without reducing the choice to a feature count. Email services can look alike because they all send messages from your domain. The useful question is what happens before and after the send. Does a person need an inbox? Does code need a webhook? Must an agent return to the same thread? Do you want to run the infrastructure yourself? This guide separates those jobs before comparing products. The quick answer is to choose a mailbox for lasting human conversations, a transactional service for application delivery, an agent inbox platform for addresses created through code, and raw infrastructure when your team wants to build and operate the missing layers. Some products now cover two categories. Startup Mail combines a company mailbox with an agent inbox control plane. ## Start with the type of service | Type | Main job | Typical examples | | ---------------------------- | ----------------------------------------------------------- | ------------------------------------ | | Company mailbox | Give people and software a lasting address and inbox | Startup Mail, Google Workspace | | Agent inbox platform | Create and manage email identities for agents through code | Startup Mail, AgentMail | | Transactional email platform | Deliver and track messages triggered by an application | Postmark, Resend, SendGrid | | Inbound email processor | Turn received email into data for another system | Postmark inbound, Resend Receiving | | Raw email infrastructure | Supply sending and receiving parts that your team assembles | Amazon SES, Cloudflare Email Service | | Marketing platform | Manage audiences, consent, campaigns, and engagement | Mailchimp, Resend Marketing | Several products span more than one row. Resend can receive mail as well as send it. Google Workspace has a broad Gmail API. Amazon SES can receive messages. The table describes each product's centre of gravity, not a hard technical boundary. ## What Startup Mail is built to do Startup Mail gives a custom-domain address a persistent mailbox. People can use the web inbox or verified forwarding. Teams can share one address while keeping another private. Software can use the REST API, SDKs, signed webhooks, or MCP. An agent control plane can provision tenants and mailboxes, manage drafts, schedule sends, and apply communication policies; administrators issue resource-scoped keys in the web app. Incoming and outgoing messages remain in the same threads across those interfaces. That makes Startup Mail a good fit when an address belongs to the company rather than only to an application or an agent. It is not a marketing platform, office suite, general SMTP service, or raw delivery product. ## Compare the closest options ### [Startup Mail vs AgentMail](https://staging.startupmail.dev/compare/agentmail-alternative.md) Both products can provision agent inboxes, isolate tenants, and manage drafts through code. Both support mailbox-scoped keys; Startup Mail keeps key issuance as an authenticated administrator action in its web app. Startup Mail also provides a built-in human mailbox workflow. AgentMail adds WebSockets, IMAP, and SMTP. Read this comparison if you are building an agent product or deciding whether an agent should use a team mailbox. ### [Startup Mail vs Postmark](https://staging.startupmail.dev/compare/postmark-alternative.md) Postmark is strongest at transactional delivery, templates, analytics, and troubleshooting. Startup Mail is strongest when the address needs a working human inbox and a stored conversation. Read this comparison if your choice is between an inbound webhook and a mailbox, or if you may use both services for different mail. ### [Startup Mail vs Resend](https://staging.startupmail.dev/compare/resend-alternative.md) Resend combines a modern sending API with inbound email, SMTP, broadcasts, contacts, tracking, and MCP. Startup Mail provides a narrower mailbox shared by people and software. Read this comparison if you need to decide whether email is mainly a product channel or a company conversation. ### [Startup Mail vs Amazon SES](https://staging.startupmail.dev/compare/amazon-ses-alternative.md) Amazon SES supplies low-level sending and receiving infrastructure. Startup Mail supplies the mailbox, storage, threads, permissions, web interface, forwarding, and developer access around that infrastructure. Read this comparison if you are weighing low unit cost against engineering and operating work. ### [Startup Mail vs Cloudflare Email Service](https://staging.startupmail.dev/compare/cloudflare-email-service-alternative.md) Cloudflare supplies transactional sending, inbound routing, Workers bindings, SMTP, and native Agents SDK hooks. Startup Mail supplies a stored mailbox, human inbox, shared access, threads, drafts, and mailbox controls. Read this comparison if you are deciding whether to build email into a Cloudflare application or use a finished mailbox service. ### [Startup Mail vs Google Workspace](https://staging.startupmail.dev/compare/google-workspace-alternative.md) Google Workspace sells Gmail with calendars, documents, meetings, storage, chat, and administration. Startup Mail sells the email part. Read this comparison if you want custom-domain email but are not sure whether your team needs the office suite that comes with it. ## Use the right decision criteria A long table of checkmarks often hides the important tradeoff. Start with these questions instead: 1. **Who owns the address?** A person, a team, an application, or a fleet of agents? 2. **Where does the lasting copy live?** In a mailbox, your database, an object store, or nowhere? 3. **Can the sender reply?** If so, who reads the answer and how is the thread preserved? 4. **Does a person need to take over?** If yes, is there a usable inbox or must you build one? 5. **How is access limited?** Check human mailbox grants, API resource boundaries, capabilities, OAuth permissions, and tenant boundaries. 6. **What kind of mail will you send?** Direct conversations, requested transactional messages, product notifications, or marketing campaigns? 7. **What must your team operate?** Count storage, parsing, queues, retries, monitoring, and abuse controls as well as the provider bill. The answers narrow the field faster than a generic feature list. ## One company may need more than one service A clean split can be better than forcing one provider to do every job. A startup might use: - Startup Mail for `founder@`, `hello@`, and shared support conversations. - Postmark or Resend for high-volume product notifications. - Startup Mail or AgentMail for inboxes created dynamically inside an agent platform, depending on the human workflow and protocol needs. - A campaign service for consent-based newsletters. - Google Workspace for employees who need the complete Google work suite. Give each address and message type one clear owner. Avoid two systems acting as the source of truth for the same mailbox. ## How these comparisons are written Startup Mail publishes these pages, so they are not independent reviews. We reduce that bias in four ways: - We check competitor facts against current official documentation. - We link to the sources used. - We state where the other product is the better choice. - We show the last review date and update pages when products change. The aim is not to award Startup Mail the most checkmarks. It is to help you choose the right email model before you choose a vendor. ## Read the underlying guides If the categories are still unclear, start with [email API vs inbox API](https://staging.startupmail.dev/guides/email-api-vs-inbox-api.md) or [transactional email vs business email](https://staging.startupmail.dev/guides/transactional-email-vs-business-email.md). If receiving is the hard part, read [inbound email webhook vs persistent mailbox](https://staging.startupmail.dev/guides/inbound-email-webhook-vs-persistent-mailbox.md). Teams avoiding a broad productivity bundle can read [how to get custom-domain email without an office suite](https://staging.startupmail.dev/guides/custom-domain-email-without-office-suite.md). Agent builders can start with [the complete guide to email for AI agents](https://staging.startupmail.dev/guides/email-for-ai-agents.md). ## Related reading - [Startup Mail vs AgentMail](https://staging.startupmail.dev/compare/agentmail-alternative.md): Compare Startup Mail and AgentMail for agent inboxes, company email, custom domains, APIs, webhooks, team access, and pricing. - [Startup Mail vs Postmark](https://staging.startupmail.dev/compare/postmark-alternative.md): Compare Startup Mail and Postmark for transactional sending, inbound email, persistent inboxes, teams, APIs, analytics, and pricing. - [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.