Connect BIGLOBE mail to Claude,
Cursor, ChatGPT, any MCP client
Give your AI agent a real BIGLOBE inbox. Read, search, send, reply, schedule and organize mail over IMAP, with the settings BIGLOBE publishes and nothing to switch on first.
Claude cannot reach BIGLOBE mail on its own. MCPEmails is a hosted MCP server that connects it over IMAP at mail.biglobe.ne.jp on port 993, authenticating with your BIGLOBE address and BIGLOBE password, so Claude, Cursor or any MCP client can read, search, send and organize that mail. BIGLOBE is one of the simpler Japanese ISPs to connect: the same host serves incoming and outgoing mail, the password is the ordinary BIGLOBE password, and there is no toggle to find in the webmail first. One inbox is free, forever.
How BIGLOBE connects: mail.biglobe.ne.jp for both directions
BIGLOBE documents one server name for everything. IMAP is mail.biglobe.ne.jp on port 993 with SSL, and SMTP is the same mail.biglobe.ne.jp on port 465 with SSL. The guide also lists 143 and 587 without SSL; MCPEmails uses the encrypted pair. The username, in the field BIGLOBE labels アカウント, is your BIGLOBE mail address, and the password is your BIGLOBEパスワード. BIGLOBE's IMAP guide lists no prerequisite and no separate mail password, which sets it apart from several other Japanese ISPs. One thing to know about the server itself: before you log in it says nothing about how it authenticates, so a client that waits for an advertised list of mechanisms sees an empty one. MCPEmails asks, gets PLAIN, LOGIN and CRAM-MD5 back, and logs in. Autodiscovery also fails for BIGLOBE, because the public Mozilla database lists only POP for biglobe.ne.jp.
The exact BIGLOBE 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) | mail.biglobe.ne.jp | 993 | TLS (implicit) |
| SMTP (outgoing) | mail.biglobe.ne.jp | 465 | TLS (implicit) |
Verified 2026-11-04: mail.biglobe.ne.jp answered a TLS connection and identified itself as an IMAP server under that name. It advertises CRAM-MD5, LOGIN, PLAIN authentication.
Sign in with: Your full BIGLOBE address, name@xxx.biglobe.ne.jp, in the field BIGLOBE's guide labels アカウント.
A BIGLOBE inbox your agent can actually use
21 action-based MCP tools: send, reply, forward, schedule, and organize. Your agent finishes the job inside BIGLOBE.
- 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 BIGLOBE 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.
Have your BIGLOBE address and password ready
The username is your BIGLOBE mail address and the password is your BIGLOBE password, the same one BIGLOBE's guide tells you to type into a mail program. There is no separate credential to create and no setting to enable in the webmail first.
Enter them in MCPEmails
Choose IMAP / SMTP, enter the address and the password. The BIGLOBE host and ports are prefilled and were confirmed from a live TLS connection.
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 BIGLOBE mailbox.
Step-by-step guides: How to connect Claude to your email · Claude IMAP connector guide
More guides: Inbox zero with AI · Give your AI agent an inbox
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 BIGLOBE in ChatGPT
ChatGPT reaches BIGLOBE through a custom MCP server, which you add on chatgpt.com with ChatGPT Go or a paid plan.
- Connect BIGLOBE 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 BIGLOBE
The banner advertises no capabilities, and some tooling gives up there
The greeting from mail.biglobe.ne.jp is a bare * OK IMAP4rev1 server ready, with no capability list and no SASL-IR. Only after an explicit CAPABILITY request does the server list AUTH=PLAIN, AUTH=LOGIN and AUTH=CRAM-MD5. Libraries that read the greeting alone and refuse to continue when it names no mechanism report BIGLOBE as unreachable while Thunderbird logs in without complaint. MCPEmails asks before deciding, so this is handled for you.
MOVE is there, IDLE is not
When probed, BIGLOBE advertised MOVE and UIDPLUS, so filing a message is one atomic command rather than a copy, a flag update and an expunge. It did not advertise IDLE, so new mail is found by polling rather than pushed: an agent sees a new message the next time it checks, not the instant it arrives. It also omits SPECIAL-USE, so the sent, drafts and trash folders are matched by name. If an agent files something in the wrong folder, name the folder in the instruction.
Your mail client may offer only POP, because the public database does
The Mozilla autoconfiguration database that many clients consult lists only POP3 for biglobe.ne.jp, so a client that fills in settings for you can silently set up a download-and-delete account instead of IMAP. BIGLOBE's own guide documents IMAP on port 993. Enter it by hand, or let MCPEmails prefill it.
Known limits with BIGLOBE
- There is no IDLE support, so mail is polled rather than pushed. Your agent sees a new message the next time it checks rather than the moment it arrives.
- The SMTP server accepts messages up to 100 MB, which is generous, but the receiving server applies its own limit. Most sit between 10 MB and 50 MB, so a large attachment BIGLOBE accepts can still bounce from the other end.
- There is no app password and no OAuth path, so the stored credential is your BIGLOBE password. Changing it disconnects the mailbox until you enter the new one.
BIGLOBE and AI: common questions
Does Claude work with BIGLOBE mail?
Not on its own. Claude has no built-in BIGLOBE 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 BIGLOBE IMAP and SMTP settings?
IMAP is mail.biglobe.ne.jp on port 993 with SSL. SMTP is mail.biglobe.ne.jp on port 465 with SSL. The username is your BIGLOBE mail address and the password is your BIGLOBE password. The host was confirmed from a live TLS connection on the date shown on this page.
Which password does BIGLOBE mail use?
The BIGLOBE password, the one BIGLOBE's IMAP guide tells you to enter in a mail program. BIGLOBE's guide lists no separate mail password and no app password.
Do I have to enable IMAP in BIGLOBE first?
BIGLOBE's IMAP setup guide lists no prerequisite: it gives the server, the ports and the credentials and nothing to switch on. If a login is refused, check the address and password before looking for a setting.
Why does my mail client suggest POP for BIGLOBE?
Because the public autoconfiguration database lists only POP3 for biglobe.ne.jp. IMAP exists and is documented by BIGLOBE at mail.biglobe.ne.jp on port 993 with SSL. Enter it by hand, or let MCPEmails fill it in.
Is my BIGLOBE mail stored on your servers?
No. Messages are fetched live from BIGLOBE over IMAP for each request and passed to your AI client. Credentials are encrypted at rest and message bodies are not retained.
Can ChatGPT read my BIGLOBE mail?
Yes, once BIGLOBE 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 BIGLOBE inbox
Connect BIGLOBE mail in minutes. One inbox free forever, no card required.