Connect Outlook to Sickle

Outlook.com, Hotmail and Live addresses — and Microsoft 365 work or school accounts — sign in with Microsoft. You never give Sickle your Microsoft password: Microsoft asks you to accept the permissions and hands Sickle a token you can revoke at any time. Microsoft no longer accepts passwords from mail apps at all, so this is the only way in.

Add the mailbox once, on the web or in the Mac app, and it shows up in both — and in every agent you have connected to Sickle.

Before you start

• A Sickle account. If you do not have one yet, start a free trial.
• Outlook.com, Hotmail and Live: Microsoft turns IMAP off by default. In Outlook.com, open Settings → Mail → Forwarding and IMAP, turn on Let devices and apps use IMAP and click Save.
• Microsoft 365 at work or school: your organisation may need to approve Sickle first. See Work and school accounts below.

Connect on the web

1. Sign in at sickle.app and open Mailboxes.
2. Click Connect mailbox and choose Microsoft.
3. Sign in to your Microsoft account and click Accept on the permissions screen. Sickle asks to read and organise your mail over IMAP and to send mail from the Mac app; your agent cannot send mail.
4. You land back on Mailboxes with "[email protected] is connected."

Connect in the Mac app

1. Click + at the bottom of the sidebar (Add mailbox). On first launch, the onboarding screen shows the same choices.
2. Choose Sign in to Outlook (⌘3).
3. Finish in your browser, then come back to the app.

Signed in to the wrong Microsoft account in your default browser? Hold ⌃ while clicking Sign in to Outlook to copy the sign-in link instead, and open it in another browser.

Check it worked

The mailbox appears in the list on the Mailboxes page with the provider Outlook. If you have an agent connected, ask it "Which mailboxes can you see?" — the new one is there, with nothing to reconnect.

Work and school accounts

Microsoft 365 organisations decide which apps can reach company mail. Two things can get in the way:

• "Need admin approval". Your organisation does not let people approve apps themselves, or not apps that read mail. An administrator can grant consent for everyone in the Microsoft Entra admin center under Enterprise apps, or turn on the admin consent workflow so you can send them a request from that screen.
• IMAP turned off for your mailbox. IMAP is on by default, but an administrator can switch it off per person: Exchange admin center → Recipients → Mailboxes → your mailbox → Manage email apps settings → IMAP.

Troubleshooting

• The sign-in works but Sickle can't read any mail. For a personal account, check Let devices and apps use IMAP is on (see Before you start). For a work account, ask your administrator whether IMAP is on for your mailbox.
• "Sign-in was cancelled in the browser." The Microsoft window was closed before you accepted. Start again from Connect mailbox.
• The app says "Can't sign in to [email protected]". The access was revoked or expired. Click Sign in on the notice and accept again.

Disconnect

On the Mailboxes page, click Disconnect next to the mailbox. To revoke Sickle on Microsoft's side as well, remove it from your Microsoft account's app permissions. For a work or school account, your administrator can remove it for you.

Next: connect your agent

Your Outlook mailbox is ready for any agent you connect to Sickle. Pick yours: Claude, Claude Code, Codex, Cursor or OpenClaw.