Connect Yahoo! JAPAN Mail to Claude,
Cursor, ChatGPT, any MCP client
Give your AI agent a real yahoo.co.jp inbox. Read, search, send, reply, schedule and organize mail over IMAP with your ordinary Yahoo! JAPAN ID password, once access from outside Yahoo! JAPAN's own apps is switched on.
Claude cannot reach Yahoo! JAPAN Mail on its own. MCPEmails is a hosted MCP server that connects it over IMAP at imap.mail.yahoo.co.jp on port 993, authenticating with your Yahoo! JAPAN ID password, so Claude, Cursor or any MCP client can read, search, send and organize that mail. Yahoo! JAPAN is a separate company and a separate mail platform from Yahoo Mail on yahoo.com: there are no app passwords, and a yahoo.com guide does not apply. What you need instead is one settings page in Yahoo! JAPAN Mail where access from outside Yahoo! JAPAN's services is allowed and IMAP and SMTP are set to on. Until that is done, a correct password is refused. One inbox is free, forever.
How Yahoo! JAPAN Mail connects: IMAP, a toggle, and your ID password
Yahoo! JAPAN documents IMAP at imap.mail.yahoo.co.jp on port 993 and SMTP at smtp.mail.yahoo.co.jp on port 465, both over SSL, and asks that the names be entered in lowercase. The username is the address you want to use or your Yahoo! JAPAN ID, and the password is the Yahoo! JAPAN ID password, the same one you sign in with on the web. There is no app password to generate. What Yahoo! JAPAN requires instead is permission: on the IMAP/POP/SMTPアクセス page in the mail settings, access from outside Yahoo! JAPAN's official services has to be allowed, and IMAP and SMTP each have to be set to on. Yahoo! JAPAN's help also notes that an account which signs in without a password, by passkey or SMS, must set one before any outside mail app can use it. This page is for @yahoo.co.jp and @ymail.ne.jp addresses. A @yahoo.com address is Yahoo Mail, a different service with its own page.
Have a @yahoo.com address instead? Connect Yahoo Mail, which uses an app password
The exact Yahoo! JAPAN Mail IMAP and SMTP settings
Copy these into the connect form. MCPEmails prefills them where it can, and retries the other standard transport if the first does not answer.
| Protocol | Server | Port | Security |
|---|---|---|---|
| IMAP (incoming) | imap.mail.yahoo.co.jp | 993 | TLS (implicit) |
| SMTP (outgoing) | smtp.mail.yahoo.co.jp | 465 | TLS (implicit) |
Verified 2026-11-04: imap.mail.yahoo.co.jp answered a TLS connection and identified itself as an IMAP server under that name. It advertises LOGIN, PLAIN, XOAUTH2 authentication.
Sign in with: Your Yahoo! JAPAN address, name@yahoo.co.jp or name@ymail.ne.jp, or your Yahoo! JAPAN ID. If you sign in with a secret ID, use the secret ID.
A Yahoo! JAPAN Mail inbox your agent can actually use
21 action-based MCP tools: send, reply, forward, schedule, and organize. Your agent finishes the job inside Yahoo! JAPAN Mail.
- 01Read
Read & search mail
List, read and search across folders to find that invoice, summarize a thread, or pull the latest from a sender.
- 02Send
Send, reply & forward
Compose and send real messages, reply in-thread, and forward, directly from your mailbox, not as a draft you finish by hand.
- 03Schedule
Schedule for later
Queue a message to go out at the right time, so your agent can draft now and send on schedule.
- 04Organize
Move, copy, flag, archive, delete
Keep the inbox tidy: file mail into folders, flag what matters, archive the rest, or delete on request.
Connect Yahoo! JAPAN Mail in four steps
From sign-up to first AI email in a couple of minutes.
Create your free MCPEmails account
Sign up at mcpemails.com. The free plan connects one inbox forever and asks for no card. Leave it open; the Yahoo! JAPAN side takes about a minute.
Allow access from outside Yahoo! JAPAN, and switch IMAP and SMTP on
In Yahoo! JAPAN Mail on the web, click the gear icon (設定) at the top right of the message list and open the IMAP/POP/SMTPアクセス page. Under Yahoo! JAPAN公式サービス以外からのアクセス choose 許可する, set IMAP, POP and SMTP to 利用する, and click 保存. Yahoo! JAPAN notes that SMTP does not work unless the others are on too, so turn them on together. If you sign in by passkey or SMS and have no password, set one first; the same help article links to the page for that.
Enter your address and your Yahoo! JAPAN ID password in MCPEmails
Choose IMAP / SMTP, enter your @yahoo.co.jp address and your Yahoo! JAPAN ID password. The hosts and ports are prefilled and were confirmed from a live TLS connection. If the address is refused, try your Yahoo! JAPAN ID in the username field instead, which is the other form Yahoo! JAPAN documents.
Paste the MCP URL into your AI client
Drop https://mcpemails.com/api/mcp into Claude, Cursor or ChatGPT, authorize, and your agent can read, search, send, reply, forward, schedule and organize the Yahoo! JAPAN mailbox.
Step-by-step guides: How to connect Claude to your email · Claude IMAP connector guide
More guides: Schedule an email from the chat · Inbox zero with AI
Use this inbox in your AI app: Claude · ChatGPT · Cursor · VS Code · Codex · Claude Code · Cline · Windsurf · Gemini CLI · All supported apps
Need the server names and ports? Look up IMAP and SMTP settings
Comparing providers first? See the email provider compatibility matrix
Use Yahoo! JAPAN Mail in ChatGPT
ChatGPT reaches Yahoo! JAPAN Mail through a custom MCP server, which you add on chatgpt.com with ChatGPT Go or a paid plan.
- Connect Yahoo! JAPAN Mail to MCPEmails with the steps above.
- On chatgpt.com, open Plugins, Personal, click Add, then Add custom MCP server.
- Name it MCPEmails, paste
https://mcpemails.com/api/mcpunder Connection, choose OAuth, confirm, click Create as a plugin and sign in to MCPEmails. - In a chat, type @ and pick MCPEmails. Do it again when a follow-up needs your mail.
What actually goes wrong with Yahoo! JAPAN Mail
Yahoo! JAPAN is not Yahoo, and a yahoo.com app password does nothing here
Yahoo! JAPAN runs its own mail service on its own servers, under yahoo.co.jp, and it is not the Yahoo Mail that serves yahoo.com. The two have different hosts, different settings pages and different rules for mail clients. Yahoo Mail refuses the account password and insists on an app password; Yahoo! JAPAN has no app passwords at all and accepts the ordinary ID password once access is switched on. A guide written for yahoo.com, including our own Yahoo Mail page, sends you to a settings page your Yahoo! JAPAN account does not have. Use this page for @yahoo.co.jp and @ymail.ne.jp, and the Yahoo Mail page for @yahoo.com.
A refused login usually means the access toggle, not the password
Yahoo! JAPAN ships mailboxes with access from outside its own apps switched off. Until Yahoo! JAPAN公式サービス以外からのアクセス is set to 許可する and IMAP and SMTP are set to 利用する, the server accepts the connection and refuses the credentials, and nothing in that error says why. Yahoo! JAPAN also documents that it turns this access off again on its own, after suspicious sign-in activity or after a long period in which no mail app used it. So a connection that worked for months can stop with a login failure while nothing changed on your side; open the same settings page and switch it back on.
Yahoo! JAPAN would rather you did not do this, and says so
The help article that documents these settings also says that password authentication over POP, IMAP and SMTP carries a risk of account takeover, recommends the web and app versions of Yahoo! JAPAN Mail instead, and suggests disabling access from mail apps once you no longer need it. That is Yahoo! JAPAN's position, and it is worth knowing before you rely on the connection. On the MCPEmails side the stored credential is encrypted at rest, and disabling the toggle in Yahoo! JAPAN cuts the connection immediately at their end, which is the quickest way to revoke it.
No MOVE, no IDLE and no SPECIAL-USE, so folders are matched by name
When probed, imap.mail.yahoo.co.jp advertised UIDPLUS and SASL-IR but neither MOVE, IDLE nor SPECIAL-USE. Filing a message therefore runs as a copy, a flag update and an expunge rather than one command, new mail is found by polling rather than pushed, and the sent, drafts and trash folders are identified by their names rather than by a role the server declares. If an agent files something in the wrong place, name the folder in the instruction.
Known limits with Yahoo! JAPAN Mail
- Access from mail apps is Yahoo! JAPAN's to switch off, and it does so after suspicious activity or long non-use. When that happens the connection fails until you re-enable it in the mail settings.
- The SMTP server announces a maximum message size of about 36 MB. A forward carrying larger attachments is refused at send time.
- There is no OAuth path for outside apps and no app password, so the stored credential is your Yahoo! JAPAN ID password. Changing it disconnects the mailbox until you enter the new one.
Yahoo! JAPAN Mail and AI: common questions
Does Claude work with Yahoo! JAPAN Mail?
Not on its own. Claude has no built-in Yahoo! JAPAN connector and cannot open an IMAP connection by itself. Connecting an MCP server such as MCPEmails to the mailbox over IMAP gives Claude read, search, send, reply, forward, schedule and organize access to it, and the same connection works from Cursor, ChatGPT and other MCP clients.
What are the Yahoo! JAPAN Mail IMAP and SMTP settings?
IMAP is imap.mail.yahoo.co.jp on port 993 with SSL. SMTP is smtp.mail.yahoo.co.jp on port 465 with SSL. The username is your yahoo.co.jp address or your Yahoo! JAPAN ID, and the password is your Yahoo! JAPAN ID password. Both hosts were confirmed from a live TLS connection on the date shown on this page.
Why is my Yahoo! JAPAN password rejected by a mail app?
Almost always because access from outside Yahoo! JAPAN's own services is still off. Open the gear icon in Yahoo! JAPAN Mail, go to IMAP/POP/SMTPアクセス, allow access from non-official services, set IMAP and SMTP to on and save. If your account signs in by passkey or SMS, you have to set a password first. If the connection used to work, Yahoo! JAPAN may have switched access off again after a period of non-use.
Does Yahoo! JAPAN Mail need an app password?
No. Yahoo! JAPAN has no app password scheme. Mail apps use the Yahoo! JAPAN ID password after access has been allowed in the settings. That is the opposite of Yahoo Mail on yahoo.com, which only accepts app passwords, so do not follow a yahoo.com guide for a yahoo.co.jp address.
Can I connect a ymail.ne.jp address?
Yes. ymail.ne.jp is a Yahoo! JAPAN address and uses the same servers, the same settings page and the same Yahoo! JAPAN ID password as yahoo.co.jp.
Is my Yahoo! JAPAN mail stored on your servers?
No. Messages are fetched live from Yahoo! JAPAN over IMAP for each request and passed to your AI client. Credentials are encrypted at rest and message bodies are not retained. Switching mail-app access off in Yahoo! JAPAN's settings ends the connection immediately at their end.
Can ChatGPT read my Yahoo! JAPAN Mail?
Yes, once Yahoo! JAPAN Mail is connected to MCPEmails. On chatgpt.com, add a custom MCP server with the URL https://mcpemails.com/api/mcp and OAuth sign-in. That works with ChatGPT Go and paid plans. ChatGPT gets only the access you approve, and your mail is fetched live, never stored.
Give your AI a Yahoo! JAPAN inbox
Connect Yahoo! JAPAN Mail in minutes once access is switched on. One inbox free forever, no card required.