To give Claude an email inbox, add nicemails as a custom connector: open Customize → Connectors, choose Add custom connector and paste the nicemails MCP server address. Sign in to nicemails and approve the permissions. Claude can then read, search and organize your mailboxes and send mail you approve, on the web and in Claude Desktop.
What do you need before you start?
A nicemails account. Sign-up is free and has no password: you sign in with a code sent to your email. If you have no mailbox yet, the approval page helps you create the first one.
A Claude plan with custom connectors. Per Claude’s help center, they are available on Free, Pro, Max, Team and Enterprise plans, and a Free plan can have one custom connector.
On Team and Enterprise plans, an Owner or Primary Owner adds the connector under Organization settings → Connectors. Members then connect to it from Customize → Connectors.
How do I add nicemails to Claude?
You need one address, the nicemails MCP server. It uses Streamable HTTP and OAuth sign-in:
https://nicemails.net/mcp
In Claude on the web or in Claude Desktop, open Customize → Connectors.
Select + Add, then Add custom connector.
Enter a name, such as nicemails, and paste the address above as the Remote MCP server URL, exactly as shown, including /mcp.
If Claude shows OAuth client options, choose Register automatically. nicemails registers clients on its own, so there is no client ID or secret to copy.
Choose Sign in now and add the connector. Sign in to nicemails in the window that opens, using the code sent to your email.
On the nicemails approval page, choose the permissions and whether Claude may use every mailbox or only one, then select Allow.
In a chat, select + at the lower left, open Connectors and check that nicemails is switched on.
Ask Claude to list your nicemails mailboxes to confirm that the connection works.
Remote connectors are stored in your Claude account, so the same connector works in Claude on the web and in Claude Desktop. You do not need to edit claude_desktop_config.json: that file is for local servers.
If you sign in to Claude Code with the same Claude account, the connector shows up there too. See Connect Claude Code.
Can I use an API key instead of signing in?
Yes, if your organization prefers a fixed credential. Claude’s connector form has a Request headers option for servers that are not signed in with OAuth. Create the key first:
In nicemails, open Settings → API keys and select Create API key.
Choose AI agent (MCP) as the key purpose.
Pick the permissions and, if you like, limit the key to one mailbox.
Copy the key. It is shown only once.
Then add the connector with the same address, choose No sign in, and add this request header with your key in place of the placeholder:
Authorization: Bearer <YOUR_API_KEY>
What can Claude do with your mailboxes?
Claude gets the nicemails tools your permissions allow. There are 8:
list_mailboxes lists the mailboxes the connection can use.
list_messages lists one folder of a mailbox, newest first.
search searches every folder of the selected mailboxes, including Spam.
get_message reads one message without marking it as read.
create_mailbox creates a new mailbox (Manage permission, account-wide connection).
move moves a message to another folder; flag marks it read, unread, starred or answered.
send_message sends from one of your mailboxes (Send permission; new recipients need your approval).
Try asking: “Check my research mailbox for the confirmation email from the conference and tell me the deadline,” or “Archive this week’s newsletters in my projects mailbox.”
Who approves what Claude does?
Permissions: the connection gets only what you choose: Read (list, search and read mail), Manage (create mailboxes, move messages, set flags) and Send. A connection can also be limited to one mailbox.
Send approval: if a recipient is not someone you emailed from the web app, or trusted at an earlier approval, within the last 30 days, nothing is sent until you approve that message on a nicemails confirmation page while signed in. An unapproved request expires after 15 minutes.
Untrusted content: tool results mark email content as untrusted, and nothing inside an email can approve a send.
Per conversation: in Claude, switch the connector off for a chat under + → Connectors when you do not want Claude to touch your mail.
An off switch: in nicemails, open Settings → API keys and disconnect Claude under Connected apps. Access ends immediately, and every tool call stays in your account’s activity history.
Troubleshooting
Claude says it cannot connect to nicemails. What should I check?
Check that the URL is exactly https://nicemails.net/mcp, including /mcp, with no spaces. If the sign-in window closed before you selected Allow, remove the connector and add it again, then finish the sign-in.
Why doesn’t Claude use nicemails in my chat?
Make sure the connector is switched on for that conversation under + → Connectors. Naming the mailbox in your request helps, for example “search my agent mailbox for the code from…”.
I’m on Claude’s Free plan and can’t add another connector.
Per Claude’s help center, a Free plan can have one custom connector. Remove the other custom connector or change your Claude plan. Any nicemails plan works, including Free.