---
title: "An AgentMail alternative for existing Gmail and Outlook"
description: "Need an email API for existing Gmail or Outlook mailboxes? Evaluate Mailera by address ownership, read-only access, sync behavior, and retention."
url: https://mailera.app/en/blog/agentmail-alternative-existing-inboxes
published: 2026-10-25
updated: 2026-10-25
---

# An AgentMail alternative for existing Gmail and Outlook

Start with the address your agent needs to use. Mailera connects mailboxes you already control, with separate permissions for reading and sending.

## TL;DR: Which mailbox model do you need?

Choose Mailera when your agent needs access to an existing Gmail, Outlook, or other supported mailbox. Mailera connects existing mailboxes; it does not create email addresses. If your workflow needs a separate, newly created agent identity, make address provisioning a selection requirement instead. Start an existing-mailbox evaluation with a group-scoped, read-only API key.

A connected mailbox is an account that already exists at an email provider. Provisioning means creating a new mailbox or address. These solve different problems, even when both workflows eventually expose email to an API.

## What should you compare when evaluating AgentMail alternatives?

For a Mailera vs AgentMail evaluation, write down the required email address before comparing SDKs or agent integrations. “Read messages already arriving in our team mailbox” and “give each agent a new address” are different requirements. For the broader selection criteria, see [Choose an email API by mailbox model](https://mailera.app/en/blog/best-email-api-for-ai-agents).

Use this table to decide whether Mailera belongs on your shortlist:

| Decision | Mailera's approach | What to check for your workflow |
| --- | --- | --- |
| Mailbox model | Connects existing provider mailboxes | Must the address already exist, or must the service create it? |
| Connection requirements | Microsoft OAuth; Gmail app password; other supported provider methods | Can you authorize access to the required mailbox? |
| Existing messages | Initially loads messages within the retention period, newest first | How much existing history does the task require? |
| Application access | REST API, MCP, and webhooks | Does your application need direct API calls or agent tools? |
| Sending | Separate key permission and mailbox sending capability | Does the agent need to send at all? |
| Operational dependencies | Provider authentication and mailbox synchronization | How will you handle a disconnected or sleeping mailbox? |

The [Mailera product overview](https://mailera.app/en/product) describes the connected-mailbox model. Check the [supported email providers](https://mailera.app/en/providers) against your actual accounts, rather than assuming that an email API can access any address.

An address on a custom domain is not, by itself, evidence of access to an existing mailbox. Keep “create an address using this domain” separate from “read the messages in this account.”

## When is Mailera the right AgentMail alternative?

Consider a team with an existing Microsoft 365 operations mailbox and a Gmail account used for supplier correspondence. The agent's job is to find incoming requests and prepare a daily summary. People already send email to those addresses, so creating another address would not meet the immediate requirement.

Mailera supports Outlook/Microsoft 365, Gmail, Yahoo, iCloud, Zoho, and custom IMAP servers. `GET /messages/search` searches across connected mailboxes and returns `mailbox_id`, `mailbox_email`, and `folder`.

![Mailera Unified inbox in a test workspace with personal content redacted.](https://mailera.app/media/cd9e7ba53410f84c/choose-an-email-mcp-server-for-your-existing-mailboxes-en-1200.jpg)
_The Unified inbox screen in a test workspace._

That context matters when the agent processes similar messages from different accounts. Keep the mailbox identity attached to each result rather than passing only a subject and body into the application.

At the API level, `GET /mailboxes` lists connections. Search operates within the key's scope, and the message fields let your application retain the source account and distinguish Inbox from Junk.

The [guide to email for AI agents](https://mailera.app/en/blog/email-for-ai-agents) explains the broader existing-mailbox workflow. For related operations, see [Unified inbox operations for AI agents](https://mailera.app/en/blog/unified-inbox-for-ai-agents).

Mailera also provides MCP tools for listing, searching, and reading messages, plus separate sending and reply tools. Applications can use the `message.received` webhook event. The [developer overview](https://mailera.app/en/developers) covers these integration paths.

### Existing access is not unlimited history

After connection, Mailera initially loads messages within the retention period, newest first. The self-serve free plan retains messages for 30 days. Connected-mailbox access should therefore not be treated as a full historical archive.

If the task depends on older correspondence, settle that requirement before building the agent around search results.

## When is a separate inbox the better choice?

A separate address is appropriate when creating an independent email identity is part of the task. For example, you might want a test agent to receive correspondence at a dedicated address rather than read an existing team account.

In that case, require the service you evaluate to support address creation. Also decide whether the application needs one persistent address or separate addresses for different workflows. Those are requirements to resolve before choosing an API.

By contrast, if the agent must summarize messages already arriving in a particular Outlook or Gmail account, evaluate access to that account first. Creating a new address does not meet that requirement, even if the application can read email from it.

Keep approval controls separate from address choice, too. A dedicated identity still needs clear rules about what the agent may read and when it may send.

## How can you validate an existing-mailbox workflow?

Run a small, read-only evaluation with a test mailbox you own. You do not need to grant sending permission to check whether the agent can find the messages it needs.

1. **Confirm the provider and account requirements.** Choose a mailbox you control and check the provider list. For Gmail, Mailera uses an app password. [Google's app-password guidance](https://support.google.com/accounts/answer/185833) requires 2-Step Verification; your account must also permit this connection method.
2. **Connect the mailbox.** As an Admin or Leader, open **Mailboxes → Add mailbox**. For Outlook or Microsoft 365, select **Sign in with Microsoft** and complete Microsoft's OAuth consent flow. The [Microsoft connection guide](https://mailera.app/en/providers/microsoft) covers this path. For other providers, follow the connection form and provider instructions.
3. **Inspect the connection and identify the expected messages.** Check the mailbox's status. In the API checks below, use `GET /mailboxes` to inspect the connection and `GET /messages/search` to verify the expected recent messages and their source mailbox through `mailbox_id` and `mailbox_email`. Where the connection flow uses **Test & connect**, the test checks sign-in without sending an email.
4. **Create a narrowly scoped key.** Open **Settings → API key → Create key**. Give it a descriptive name, select one test group under **Mailbox scope**, and grant **Read** without **Send messages**. Set **Expiration** for the evaluation.
5. **Test listing and search.** Check that the API exposes the intended mailbox and messages. Only then decide whether the application needs sending permission or a different address model.

![Connected test mailboxes in Mailera with provider, status, and last synchronization information.](https://mailera.app/media/d3a7a0d58e4ce6d0/an-agentmail-alternative-for-existing-gmail-and-outlook-en-1200.jpg)
_Check provider connection status separately from API-key permissions._

Store the key in your local environment as `$MAILERA_API_KEY`. List a connected mailbox:

```bash
curl --fail-with-body \
  'https://mailera.app/api/public/v1/mailboxes?limit=1' \
  -H "Authorization: Bearer $MAILERA_API_KEY"
```

Inspect `provider`, `status`, and `capabilities`. In particular, `capabilities.send` describes the mailbox's sending capability; it does not replace the API key's separate sending permission.

Next, search for a harmless subject term used in your test messages:

```bash
curl --fail-with-body --get \
  'https://mailera.app/api/public/v1/messages/search' \
  -H "Authorization: Bearer $MAILERA_API_KEY" \
  --data-urlencode 'q=evaluation' \
  --data-urlencode 'limit=5'
```

Check each result's `mailbox_id`, `mailbox_email`, and `folder`. An empty result is a reason to inspect the test message, key scope, and synchronization state, not an automatic reason to grant more permissions.

## What mistakes cause the wrong choice?

### Assuming a connected mailbox can send

Receiving and sending are separate checks. If the outgoing connection fails, Mailera can offer **Save as receive-only**. That may be sufficient for a summarization or classification agent.

Before enabling outbound actions, check both the mailbox capability and the key's **Send messages** permission.

### Expecting every message immediately

Mailera uses Microsoft Graph change notifications for Microsoft mailboxes, with periodic background checks as a fallback. [Microsoft's Outlook notification documentation](https://learn.microsoft.com/en-us/graph/outlook-change-notifications-overview) describes subscriptions to mailbox message changes.

Background checks also vary with mailbox activity. Idle mailboxes are checked less often, and inactive mailboxes can sleep and wake on use. Do not design the workflow around instantaneous synchronization. Inspect `sync` and `last_sync_at` when troubleshooting freshness; [mailbox sync recovery](https://mailera.app/en/blog/mailbox-sync-troubleshooting) covers that operational task.

### Treating provider sign-in as an API-key issue

A key authorizes your application to call Mailera. The mailbox connection authorizes access to the provider account. Check these separately: broader key permissions will not repair a broken provider sign-in.

### Choosing outside Mailera's intended scope

Mailera does not support Proton Mail or Tuta. It also does not provide bulk or marketing sending or mailbox warmup, and it cannot control a provider's inbox placement decisions. These are product boundaries, not settings to enable during integration.

## How should you limit an email agent's access?

Treat incoming email as untrusted data, not instructions. A message that tells the agent to reveal credentials, change its rules, or send private content elsewhere must not become an authorized action. This is the prompt-injection boundary in an email workflow.

Start with **Read** and one mailbox group. A read-only key still exposes message content, so restrict the group to accounts the application actually needs. Keep keys out of prompts, screenshots, and logs.

![Mailera API-key configuration limited to one mailbox group with read-only permission.](https://mailera.app/media/217ef7f9fc71e178/why-a-mailera-mailbox-goes-to-sleep-and-how-to-wake-it-wake-en-1200.jpg)
_Start with one mailbox group and Read permission; add sending only when the task requires it._

If you later enable sending, require human confirmation in your application before the send request. Show the recipient and complete outgoing message for approval. Treat that confirmation as an application responsibility, not something implied by granting **Send messages**.

Set an expiration when creating a key and revoke it when the evaluation ends. Mailera rejects calls immediately after revocation. Review the [Mailera security information](https://mailera.app/en/security) alongside your application's own access controls.

Use owned test accounts throughout the evaluation. Redact addresses and message bodies in shared examples, and never include credentials in screenshots.

**Connect your first mailbox in 2 minutes** — Add an Outlook, Gmail or IMAP mailbox and read email messages in the app or via the API. [Connect mailbox](https://mailera.app/auth?mode=signup)