An AgentMail alternative for existing Gmail and Outlook

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.

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

The Mailera product overview describes the connected-mailbox model. Check the supported email 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.

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 explains the broader existing-mailbox workflow. For related operations, see Unified inbox operations 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 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 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 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.

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

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:

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 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 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.

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 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.