Connect iCloud Mail to Sickle

iCloud does not let mail apps sign in with your Apple Account password. Instead, you create an app-specific password — a separate password that only works for mail and that you can revoke on its own — and give that to Sickle. Sickle already knows Apple's server settings, so there is nothing else to fill 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.
• Two-factor authentication on your Apple Account. Apple only offers app-specific passwords to accounts that have it, and most accounts do.
• iCloud Mail turned on, with an @icloud.com address. If you have never used it, create the address at icloud.com/mail or on your Mac in System Settings → your name → iCloud → Mail. Older @me.com and @mac.com addresses work too.

Create an app-specific password

1. Sign in at account.apple.com.
2. In Sign-In and Security, choose App-Specific Passwords.
3. Click Generate an app-specific password, name it Sickle and follow the prompts.
4. Copy the password. It looks like xxxx-xxxx-xxxx-xxxx, and Apple shows it only once.

Apple's own instructions are in Sign in to apps with your Apple Account using app-specific passwords.

Connect on the web

1. Sign in at sickle.app and open Mailboxes.
2. Click Connect mailbox and choose iCloud.
3. Enter your iCloud email address and paste the app-specific password.
4. Click Connect. Sickle signs in to iCloud to check the password before it saves anything; you see Checking… while it does.

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 iCloud (⌘2).
3. Enter your email address and paste the app-specific password. Generate password opens Apple's instructions if you skipped the step above.
4. Click Sign in.

Check it worked

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

Troubleshooting

• "Authentication failed" or "The mail server rejected these credentials". You pasted your Apple Account password, or the app-specific password has a typo. Generate a new one and paste it rather than typing it.
• It worked, then stopped. Changing or resetting your Apple Account password revokes every app-specific password. Generate a new one; the Mac app shows a Can't sign in notice where you can enter it.
• No App-Specific Passwords option. Your Apple Account does not have two-factor authentication. Turn it on, then come back.

Disconnect

On the Mailboxes page, click Disconnect next to the mailbox. To cut Sickle off on Apple's side as well, revoke the Sickle password under Sign-In and Security → App-Specific Passwords at account.apple.com.

Next: connect your agent

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