Set-up guide
Connect any IMAP mailbox with settings you already have.
Fastmail, Zoho, a mailbox your web host set up years ago. If it speaks IMAP and SMTP over TLS, it connects with the same four settings your existing mail client is already using.
- Time About 3 minutes
- You will need Four settings
- Encryption TLS, always
The short version
Open the account settings in the mail client you already use, copy the incoming and outgoing server names, and paste them into the control panel with your username and password. If you have a working mail client, you already have everything this needs.
Who it suits
Who this path is for
Use this if your mail is not on Gmail or Microsoft 365. That covers more people than it sounds like: a mailbox that came with your web hosting, an independent provider such as Fastmail or Zoho, a mailbox your IT company set up on a server somewhere, or a domain you have had since before either of the big two mattered.
If you are on Gmail or Microsoft 365, use the Gmail guide or the Microsoft 365 guide instead. Both connect in ways that suit those providers better than plain IMAP does, and for Microsoft 365 plain IMAP with a password is not possible at all.
Before you start
The four settings you need
The same four any mail client asks for, which means you have supplied them before even if you do not remember doing it.
- Incoming server (IMAP) imap.example.com : 993
- Outgoing server (SMTP) smtp.example.com : 465
- Username usually the full address
- Password or an app password
- Anything installed nothing
Where to look
Where to find them
In order of how quickly they give you an answer:
- The mail client you already use. Every desktop and phone mail app keeps these in account settings, and they are already known to be correct, which is more than can be said for a settings page written five years ago.
- Your provider's help pages. Search for the provider name and "IMAP settings". Providers keep these current because every new customer needs them.
- Your hosting control panel. If the mailbox came with web hosting, cPanel and Plesk both have a "connect devices" or "mail client configuration" screen that prints the exact values.
What they usually look like
The shape is nearly always the same. Confirm the exact host names with your provider rather than assuming, because the pattern below is a good guess and a good guess is not the same as correct.
| Setting | Typical value | Notes |
|---|---|---|
| Incoming (IMAP) | imap.yourprovider.com, port 993 |
Implicit TLS. Port 143 is the unencrypted port and is not offered here. |
| Outgoing (SMTP) | smtp.yourprovider.com, port 465 |
Implicit TLS. Some providers use 587 with STARTTLS instead; both are fine. |
| Username | Your full email address | A few older hosts use a short system username instead. |
| Password | Your mailbox password | Some providers require an app password. Fastmail and iCloud both do. |
On hosting-provided mailboxes
If your mailbox came with your website hosting, the servers are often
mail.yourdomain.com rather than anything naming the host
company. That looks wrong and is usually right.
Walkthrough
Connect the mailbox, step by step
-
Find your IMAP and SMTP settings
Collect the four values above. Copying them out of a mail client that is currently working is the fastest route and the least error-prone.
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Add the mailbox in the control panel
Choose Add mailbox, pick IMAP, and enter what you collected. Where your provider offers a choice, use port 993 for IMAP and 465 for SMTP.
Use the TLS ports if your host offers them
TLS is supported and it is what we would rather you used: on 993 and 465 the session is encrypted before your password is sent. It will also connect on a plaintext port if that is genuinely all your host offers, which is the right behaviour for an old internal server that would otherwise be unreachable, and it means your password and your mail cross the network in the clear. Your settings decide, exactly as they do in any mail client. Use 993 and 465 unless your provider tells you otherwise.
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Check the connection
Ask Claude to list your five most recent messages. If they are the messages you expect, the mailbox is connected and nothing has been marked as read.
Not supported
Providers this cannot work with
Worth knowing before you sign up rather than after, so here they are plainly.
Proton Mail
Proton Mail reaches IMAP only through Proton Mail Bridge, which is an application that runs on your own computer and decrypts your mail locally. A remote server cannot reach a bridge running on your laptop, so Mailbox MCP cannot connect to Proton however correct the credentials are. That is Proton's design working exactly as intended, and it is a reasonable thing for them to have chosen.
Microsoft 365, over IMAP with a password
Not a Mailbox MCP limitation and not something a setting can fix. Microsoft disabled Basic Authentication for IMAP on 1 October 2022, so no client can open those mailboxes with a password. Use the Microsoft 365 path, which takes one sign-in.
Troubleshooting
If something goes wrong
Authentication fails but the password is right
Two usual causes. Either your provider wants an app password rather than your account password, which Fastmail and iCloud both do, or your username is a short system name rather than your full email address, which some older hosting setups use.
Mail reads but sending fails
IMAP and SMTP are separate services and can fail independently. Check the outgoing server name and port on their own. A provider that uses 587 with STARTTLS rather than 465 is common and entirely fine.
Folders have names you do not recognise
IMAP hosts disagree about folder naming, and some prefix everything with
INBOX. so your sent mail is INBOX.Sent. Nothing
is wrong. Ask for the folder by the name your mail client shows you.
Sent mail is not appearing where you expect
On some IMAP hosts a folder exists but is not subscribed, and mail clients that list only subscribed folders will hide it. Subscribing to the folder in your mail client makes it visible again and breaks nothing.
The diary
An IMAP mailbox can have a full calendar too
IMAP is a mail protocol and there is no diary inside it. That is where most integrations stop, and it is why an assistant connected to an ordinary mailbox can read your week only by reading emails about it. Most hosts run a calendar server alongside the mail one, speaking CalDAV, with an address of its own. Fastmail, iCloud, Nextcloud and StackMail all publish one, and so do most of the hosts that reach this page.
One field connects it: the address of that calendar server. Not a second account with us, not a second connector in your AI client, not a second thing to pay for. You paste the address, we open it while you wait, and if it opens the calendar tools appear on the connector you already set up. If it does not open, nothing is stored and you are told which of the address and the password was refused.
What your assistant can then do with the diary
Read the week and search it by subject, location or organiser. Open one event with everybody who was invited and how each of them answered. Ask when a group of people are free and get back busy blocks rather than the contents of their diaries. Book your own time, move it, repeat it weekly. Invite people to a meeting, add an online meeting link, reschedule it and tell everybody, or cancel it with a message. Accept or decline an invitation that has come in.
A recurring meeting appears on every date it falls on, the way it does in Outlook, rather than once as a rule nobody can read. Every time comes back in your calendar's own timezone, stated rather than assumed. Somebody whose calendar cannot be read comes back as unknown and never as free, which is the distinction that decides whether a meeting gets booked over their afternoon.
What a CalDAV calendar can do is settled by asking it
CalDAV servers differ, genuinely and widely. RFC 4791 defines a store for calendar entries and says nothing at all about sending an invitation; RFC 6638 added that years later and plenty of servers never followed. A server without it will accept a meeting with people invited, answer that it worked, and tell nobody, which is the worst possible failure because it is invisible from both ends.
So we ask the server what it implements at the moment it connects, and hand your assistant only the tools it actually answered for. A store-only calendar gets reading, searching and your own time; one that implements scheduling gets the meeting tools as well. Nothing is offered that would then be refused, and the control panel shows you the list your particular server gave.
How AI calendar scheduling works, end to end, and what connecting a calendar involves.
Limits
What this connection does not do
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TLS follows your ports
Encryption follows the ports you enter rather than being forced. TLS is supported and preferred; use 993 and 465 wherever your host offers them.
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One mailbox each
One connection is one mailbox on one host.
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Connect the diary as well
IMAP is a mail protocol with no calendar inside it, so connecting the mailbox does not connect the diary. Most hosts run a calendar server alongside the mail one and it has its own address, which you give us separately. How the calendar connects.
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10 MB a message
Attachments are capped at 10 MB a message in total, not per file. A file already in your mailbox can use all of it; one the assistant writes itself is far smaller.
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A file the assistant writes itself
Only a file the assistant composes itself is small. Files already in the mailbox, at a web address, or uploaded through a one-off link are streamed at send time and never pass through the model.
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Your host's send limits
Your host may impose its own send limits, and those still apply.
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Not a backup tool
It is not a backup, an archive or a migration tool.
Attribution
Sources
- Proton Mail Bridge Why Proton mailboxes are reachable only from the machine running Bridge.
- Fastmail: IMAP, POP and SMTP settings An example of a provider that issues app passwords for mail clients.
- RFC 8314: cleartext considered obsolete The standard behind refusing unencrypted mail ports.
Connect an IMAP mailbox.
The free tier is 5 calls a day on any mailbox, which is enough to find out whether your host behaves the way this page expects before you pay anything.