SickleEvery mailbox you own.
One native Mac window.
Gmail, Outlook, iCloud, Fastmail, any IMAP — in one fast app with a colour per account. And your AI agent can use every one of them too.
Version 1.0.81 · 23.9 MB · macOS 27 or later · notarized by Apple
You work the inbox. So does your agent.
Same accounts, same folders. When it archives something it is gone from the app, because there is only one mailbox.
- What’s waiting on a reply from me, across all my accounts?
- list_accounts→ 2 mailboxes: personal, work
- search_emailsboth mailboxes→ 2 threads need you
- read_email_bodyRe: SOW v3→ signed copy by Friday
- Thanks. Archive the newsletters.
- move_email3 messages → Archive→ done
- Two things need you: Eleanor wants the signed SOW back by Friday, and Ledgerly has a filing due in 51 days. I archived three newsletters.
3D model: “MacBook Pro M3 16-inch 2024” by jackbaeten, CC BY 4.0
Every account, one window.
Native, fast, and every mailbox side by side. Click around — this is the app’s own layout.
Gmail and Outlook over OAuth. Everything else over IMAP.
No cap on accounts. Sign in to Gmail, Outlook, iCloud, Yahoo or Mail.ru from one sheet, or point Sickle at any IMAP server — Fastmail, your company’s, your own — with a host, a port and a password.
GmailOAuth
Outlook / 365OAuth
iCloudapp password
Fastmailapp password
Yahooapp password
Any IMAP hostmanualAlways know which account you’re in.
Every mailbox gets its own colour — a new one picks one nobody else is using, and you can change it from the account’s menu. So you never reply to a client from your personal address.
Pick a colour in the menu · this mailbox is Blue
Get the inbox back to zero. ⌘⇧K.
One place for the mail you never meant to keep, sorted so you can clear it in a few clicks.
- Unsubscribe from mailing lists — every newsletter in one list, with how many you actually opened. Unsubscribing clears its old mail too.
- Old emails you will never read again.
- Unread for more than five days — read them all at once.
- By sender — the people filling your inbox, deletable in one go.
- One-time codes and confirmation links spotted in the list. ⌘Y copies the code.
Your agent works the same inbox.
Sickle is also an MCP server. Add it to Claude, Codex or Cursor and your agent can search, read and tidy the mailboxes in this app.
Not one Gmail account — all of them, through one connection.
Read, or read and change, granted per client and revocable any time. Nothing it does is permanent.
It runs on our server, so it works from an agent on any OS.
Same mailboxes. Whatever the agent archives is gone from the app, because there is only one inbox.
Connect an agentYour hands stay on the keys.
Compose with C, reply with R, send with ⌘↩. Jump between pinned folders with ⌘1–⌘9, filter to unread with ⌘U. And the list moves like Vim: j and k, gg to the top, dd to delete.
How the Vim keys workWhere Sickle fits.
| Sickle | Apple Mail | Mimestream | |
|---|---|---|---|
| Native Mac app | yes | yes | yes |
| Gmail | yes | yes | yes |
| Outlook, iCloud, any IMAP | yes | yes | no — Gmail only |
| Your AI agent can use your mailboxes (MCP) | yes | no | no |
| Price | subscription | free, built in | subscription |
One subscription. The agent connector included.
Every feature, every mailbox, and the connector for your agent — not a separate add-on. Free to try first.
See pricingAsked before you ask.
Do I need the Mac app to use the connector?
No — the app is optional, and the connector works from any OS. Sign in at sickle.app and add your mailboxes there: Gmail, Outlook, iCloud, Yahoo or any IMAP server. The connector signs in with the same account, so your agent sees every mailbox you add, on the web or in the app.
Do you store my email?
The app keeps a cache of your mail on your Mac, in its own sandboxed container, and erases it when you sign out. Your mailbox sign-ins are kept by your Sickle account, which is what lets an agent reach your mail without your Mac being on.
My company runs its own mail server. Does it work?
Yes. Anything with an IMAP host, a port and a password.
More than one account?
As many as you have, in one window and through one agent connection. There is no cap on accounts.
Windows or iOS?
The app is macOS only; there is no Windows, Linux or iOS app yet. The agent connector is not tied to an OS, so your mailboxes are reachable from an agent on any of them.
Is the connector included in the subscription?
Yes. One subscription covers the Mac app and the agent connector; the connector is not a separate add-on.
What happens after the free trial?
The card you gave at checkout is charged for the plan you picked, monthly or yearly, unless you cancelled before the trial ended. Nothing is charged during the trial.
Can I use the app without the connector?
Yes. The connector is included, but no agent can reach your mail until you add Sickle to one and approve the access it asks for.