Kestrel vs Mimestream

Mimestream is a native Mac email app for Gmail, built on the Gmail API, with iPhone and iPad apps in beta. Like Kestrel, it keeps your mail on your Mac and syncs straight with Google, with no sync service in between. Kestrel also takes IMAP accounts, such as Proton Mail, Fastmail and iCloud, and has AI that runs on your Mac or on your own Anthropic key.

At a glance

Feature	Kestrel	Mimestream
Price	$20 a year, on up to 3 Macs	$49.99 a year, or $4.99 a month
Platforms	Mac	Mac; iPhone and iPad in beta
Mail accounts	Gmail and any IMAP account	Gmail only
Mail passes through	Your provider, and Anthropic if you add a key	Only Gmail
AI	On your Mac, or with your own Anthropic key	Apple's Writing Tools
Account needed	None, a license key	None, a license

Straight to the provider

Mimestream and Kestrel both talk to your provider from your Mac, with no sync service of their own in between. Mimestream's service relays push notifications as opaque history IDs and handles licenses. Kestrel's own servers check the license key and offer updates.

You sign in to Mimestream with Google. Kestrel comes without a Google project, so for Gmail you create a free Google Cloud project of your own, which takes about five minutes, and sign in through it.

Gmail, or Gmail and IMAP

Mimestream is for Gmail only. Kestrel takes Gmail and Google Calendar, and any IMAP account for mail: Proton Mail through Proton Mail Bridge, Fastmail, iCloud Mail or your own server. In Kestrel, IMAP accounts have no calendar and keep recent mail only.

AI

Mimestream uses Apple's Writing Tools to rewrite what you type. Kestrel writes and rewrites drafts, summarizes threads, answers questions about your mail and labels new mail, on Apple Intelligence or on your own Anthropic key.

Pick Kestrel if

You use Proton Mail, Fastmail, iCloud or another IMAP account next to Gmail.
You want summaries, Ask AI and drafts written for you, on your Mac or your own Anthropic key.
You want to pay $20 a year for up to 3 Macs.

Pick Mimestream if

You want an app for iPhone and iPad. Kestrel is Mac only.
You don't want to create a Google Cloud project.
Your Mac runs macOS 14. Kestrel needs macOS 15 or later.

The details

Detail	Kestrel	Mimestream
Price	$20 a year for a license key, bought on account.laibe.cc. One key works on 3 Macs. The demo inbox, with made-up mail, is free to try.	$49.99 a year or $4.99 a month, with family sharing on the individual plan. A 14-day free trial, no credit card. A subscription is the only way to buy it.
Platforms	Mac only, on macOS 15 or later. A direct download, not on the Mac App Store, and it updates itself.	Mac, on macOS 12 or later; updates after version 1.10.8 need macOS 14. iPhone and iPad in beta on TestFlight, on iOS 26, for annual subscribers or monthly ones with six months paid. Sold directly by Mimestream.
Mail accounts	Gmail and Google Calendar, through a free Google Cloud project you create yourself in about five minutes. Any IMAP account for mail, with Proton Mail (through Proton Mail Bridge), Fastmail and iCloud Mail filled in for you. IMAP accounts have no calendar and keep recent mail only, such as the latest 400 in the inbox.	Gmail only, through the Gmail API, with several accounts and a unified inbox. Mimestream says Microsoft 365, Outlook and IMAP are planned.
Where your mail goes	Straight between your Mac and Google or your IMAP server. Kestrel's own servers see no mail. account.laibe.cc checks the license key, and kestrel.laibe.cc offers updates if you allow it. Sign-ins, mail passwords and API keys stay in the macOS keychain. Read statuses, team comments and booking pages need a team server you deploy to your own Cloudflare account.	Mail and sign-in tokens are stored on your Mac, and the app syncs straight with Google's APIs. Mimestream says its services have no access to your Google account or mail. Its push relay passes on only opaque history IDs, and license activation sends a hashed email address and device details.
AI	Kestrel AI writes and rewrites drafts, summarizes threads, answers questions about your mail and labels new mail. It runs on Apple Intelligence on your Mac (macOS 26), or on Claude with your own Anthropic API key, which sends the text a feature needs to Anthropic. Auto Labels is on by default, and every part can be turned off. AI apps such as Claude Code can search, triage and draft through its MCP server, never send.	Apple Intelligence Writing Tools in the composer, including the ChatGPT extension, since version 1.5. Mimestream's site lists no AI features of its own.
Keyboard	Every action has a key: E marks done, H sets a reminder, # trashes, / searches. ⌘K finds any action or folder by name and shows its key. A practice inbox teaches the first keys.	Three shortcut sets, Default, Apple Mail and Gmail, in Mimestream's settings. Any shortcut can be changed in macOS's own app shortcut settings.
To sign up	No Kestrel account. You sign in to Google or your IMAP server, and add a license key.	No Mimestream account. You sign in with Google, and activation asks for the email address the license is under.

Sources

Mimestream’s side was checked against these pages on October 29, 2026. Write to [email protected] if something has changed.