Connect multiple Gmail accounts to Claude with Mailera MCP

Can you connect multiple Gmail accounts to Claude?

Yes, through Mailera’s MCP connection: connect each Gmail mailbox, scope a Read key to their group, and use Copy MCP config in a compatible Claude client. Keep the mailbox identities separate even when you search them together.

MCP is the protocol an AI client uses to discover and call tools. Here, those tools connect Claude to Mailera, which connects to your existing inboxes. The Mailera MCP overview explains that connection; the broader guide to email MCP servers for existing mailboxes covers the architecture.

Do not give Claude your Gmail app passwords. It uses the Mailera key instead.

What do you need before connecting both inboxes?

Use two existing Gmail or Google Workspace mailboxes you own or are authorized to access. You also need an Admin or Leader role to add them in Mailera.

The Mailera Gmail connection uses app passwords, not Google OAuth. Google recommends “Sign in with Google” when an app offers it; this connection follows Google’s app-password requirements instead.

Google’s app-password guidance requires 2-Step Verification. The option may be unavailable for accounts using only security keys for 2-Step Verification, accounts with Advanced Protection, or work and school accounts. For personal Gmail accounts, IMAP access is always on, so there is no separate toggle to check there.

For Workspace, check the organization’s policy first. Google’s administrator guidance for POP and IMAP explains that administrators can disable IMAP or restrict it to specified OAuth clients. Mailera cannot override those restrictions.

Choose a mailbox group containing only the inboxes intended for this workflow. Do not include unrelated client mailboxes just because they are in the same workspace. Combining personal and work email also needs to fit your organization’s rules.

How do you connect both Gmail accounts to Mailera?

1. Open Mailboxes → Add mailbox → One mailbox. Enter the first address in Email address, check the detected provider, and select Continue. For a Workspace domain, confirm that Gmail is selected rather than assuming detection is correct.
2. Follow Google’s app-password instructions for that account. Enter the app password in Password, not your ordinary Google sign-in password. Choose the intended Mailbox group, then select Test & connect. The test does not send an email.
3. Wait for Connected <email>, then repeat with the second account and its own app password. Select the same intended group.
4. After creating the Read key in the next section, use the mailbox-list REST request shown later to inspect each mailbox’s email, status, and last_sync_at. A successful first connection does not tell you whether the second mailbox is ready.

The Gmail MCP app-password walkthrough covers credential setup in more detail. Keep passwords out of prompts, screenshots, and copied notes.

Mailera initially loads messages within the retention period, newest first. The free plan retains messages for 30 days, so a connected inbox does not mean Claude can search your complete Gmail history.

How do you give Claude access to both inboxes?

5. Open Settings → API key tab → Create key. Give the key a Descriptive name, such as “Claude Gmail reading,” and set Mailbox scope to the group containing the two inboxes. Avoid the all-groups option.
6. Select only Read and choose an Expiration. Leave Send messages, Move messages, and the other permissions disabled. Copy the key when Key created — copy it now appears; it is shown only once.
7. Use Copy MCP config for Claude. Keep the credentials in the client’s supported MCP configuration, never in a chat message. Use the Mailera Claude integration guidance for the client-side setup rather than transferring menu instructions between Claude web, Desktop, Code, and Cowork.
8. Once the client loads the tools, ask Claude to call list_mailboxes. Check that both expected addresses appear and that mailboxes outside the selected group do not.

The MCP endpoint is https://mailera.app/api/public/v1/mcp. Mailera authenticates requests with an Authorization: Bearer header; the copied configuration belongs in a client setup that supports that authentication path.

The initial task needs list_mailboxes, search_messages, and get_message, all of which require the read scope. A Read-only key cannot authorize send_email or move_message. For other tasks, see the Mailera MCP tools guide.

How do you verify that Claude keeps the inboxes separate?

Place a harmless message in each authorized inbox, with different subjects. For example, use “Mailbox test — personal” in one and “Mailbox test — work” in the other. Record the actual destination address beside each subject before asking Claude to search.

Start with this prompt:

Search both connected Gmail inboxes for the mailbox test messages. Group results by mailbox address and include the subject. Use the source mailbox from the tool results, not an address inferred from the message text. Do not move or send anything. If the source mailbox is unclear, stop and tell me.

list_mailboxes establishes which accounts are available. search_messages locates messages; get_message retrieves a message’s content. Have the client use each tool’s declared parameters rather than inventing arguments from a REST example.

The MCP tools specification defines discovery through tools/list and parameters through each tool’s inputSchema. A REST parameter name is not automatically an MCP argument name.

Run the account-specific checks before the combined search. Fill in the observed-result column yourself:

Do not accept headings such as “Personal” and “Work” as proof. Claude could infer them from subjects. Require the source account from the tool output, or resolve the returned mailbox ID to its address.

For a direct identity check outside Claude, this REST request lists mailboxes visible to the same key:

curl --fail-with-body \
  -H "Authorization: Bearer $MAILERA_API_KEY" \
  'https://mailera.app/api/public/v1/mailboxes?limit=100'

Set $MAILERA_API_KEY privately in your shell first. In the response, match data[].id to data[].email and check group_id, status, and last_sync_at for each mailbox. REST message results also include mailbox_id and mailbox_email; use those fields when inspecting REST results, not as assumed MCP field names.

If the MCP output gives you neither a source address nor an ID you can resolve, stop. Do not use that combined search for account-specific decisions until attribution is clear.

What commonly goes wrong?

Only one mailbox appears. Check that the second mailbox connected successfully and belongs to the key’s selected group. Do not widen access to all groups as a shortcut.

The app password is unavailable or rejected. Check Google’s eligibility rules and your administrator’s policy. Google also revokes app passwords when the Google Account password changes, so a previously working connection may need a new app password.

Claude cannot load the tools. Check the client’s MCP configuration and authentication support. Then check key expiration, revocation, and any IP restrictions. Inspect settings without printing credentials into chat or logs.

Recent messages are missing. Check connection status and last sync. Mailera checks active mailboxes more often than idle ones; inactive mailboxes can go to sleep and wake up again when they're used. Synchronization is not guaranteed to be instantaneous. The sync_mailbox tool requires the separate Sync permission, so the Read-only key cannot invoke it.

Older messages are missing. Check retention before treating this as a failed connection. Initial loading is limited to the retention window.

A message is attributed to the wrong inbox. Resolve the source mailbox ID to its address, then repeat the single-mailbox search. Do not ask Claude merely to relabel the same unverified summary.

How do you keep personal and work email safe?

Treat incoming email as untrusted data, not instructions. A message asking Claude to reveal secrets, change configuration, or send information elsewhere is content to analyze, not authority to act. Apply that rule even when the message appears to come from someone you know.

Use the smallest mailbox group and only the permissions needed. Read-only access still exposes sensitive email. Prompt wording cannot replace the key’s enforced scope, and putting two inboxes together does not make sharing their contents appropriate. The broader guide to email for AI agents covers using existing mailboxes; review Mailera’s security information before granting access to work mail.

Keep this workflow read-only. If you later enable sending, require confirmation of the sending mailbox, recipients, and message content before every send.

To stop the workflow’s access, revoke its Mailera key and remove the client configuration. Mailera rejects calls immediately after revocation. Revoking a Google app password separately removes access through that password.

Mailera connects existing mailboxes; it does not create Gmail accounts or email addresses.