Connect any IMAP mailbox to Sickle

Sickle reads mail over IMAP, the standard every mail provider speaks, so anything with an IMAP server can be connected: Yahoo, Mail.ru, GMX, Zoho, a web host's mailbox, your company's own server. Gmail, Outlook, iCloud and Fastmail have their own guides with fewer steps — see the list at the end.

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.
• Your provider's IMAP and SMTP server names and ports. Search its help pages for "IMAP settings"; they are usually listed together.
• The right password. Many providers refuse your normal password in mail apps and ask you to create an app password instead. If yours offers one, use it.

Yahoo and Mail.ru

Yahoo and Mail.ru have their own buttons, so you only need an email address and an app password — Sickle fills in the servers.

• Yahoo. On Yahoo's Account Security page, under External connections, click Create app password, name it Sickle and click Generate password. Then choose Yahoo in Connect mailbox on the web, or Sign in to Yahoo (⌘4) in the Mac app. If Yahoo says something went wrong, create the password in the Yahoo Mail app or in a browser you sign in to Yahoo with every day — Yahoo decides automatically who may create one.
• Mail.ru. Create a password for external applications, then choose Mail.ru on the web or Sign in to Mail.ru (⌘5) in the app. Some Mail.ru accounts also need a Mail Space subscription to use mail apps.

Find your server settings

You need four values. Typical ones look like this:

• IMAP server — imap.example.com, port 993. This is how Sickle reads your mail.
• SMTP server — smtp.example.com, port 587. The Mac app sends the mail you write through it. Your agent never sends mail.

Sickle connects to IMAP over an encrypted connection from the first byte — what providers call SSL/TLS, almost always on port 993. A server that only offers an unencrypted port 143, or STARTTLS on 143, will not connect.

Some common providers:

• GMX — imap.gmx.com, port 993. Turn on Send and receive emails via external program under Settings → POP3 & IMAP in GMX first.
• Zoho Mail — imap.zoho.com, port 993, or imappro.zoho.com for a paid account on your own domain. Turn on IMAP Access under Settings → Mail Accounts first.
• Your company's server — ask whoever runs it for the IMAP and SMTP settings, or copy them from a mail app that already works.

Connect on the web

1. Sign in at sickle.app and open Mailboxes.
2. Click Connect mailbox and choose Other.
3. Enter your email address and password, then the IMAP server and port and the SMTP server and port.
4. Click Connect. Sickle signs in to the IMAP server to check everything before it saves; 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 Manual authorisation (⌘7).
3. Enter your email address. Under Inbox settings (IMAP), enter the password, server and port; under Outbox settings (SMTP), the same password with the SMTP server and port.
4. Click Sign in.

Check it worked

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

Troubleshooting

• "Could not reach the mail server". The server name or port is wrong, or the server only accepts unencrypted or STARTTLS connections. Check you used the SSL/TLS port, usually 993.
• "Authentication failed" or "The mail server rejected these credentials". The password is wrong, or your provider wants an app password instead of your normal one.
• Your server needs a username that is not your email address. Sickle signs in with your email address as the username, so a server that expects a different login name will not accept it yet.
• Proton Mail. Proton has no IMAP server on the internet; its Bridge app runs on your own computer, where Sickle cannot reach it.

Disconnect

On the Mailboxes page, click Disconnect next to the mailbox. If you created an app password for Sickle, delete it in your provider's settings too.

Next: connect your agent

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