Updated May 1, 2026

Email client comparisons

A practical guide for choosing an email client when you use more than one provider, more than one device, or both. Epistles is not the right answer for everyone. This page explains where it fits, where other clients are stronger, and which comparison is worth reading next.

How to read these comparisons

Most email client comparisons either turn into a sales page or reduce real workflow differences to a grid of checkmarks. That is not useful if you are deciding where your mail, calendar, contacts, and account credentials should live. The pages linked here focus on the questions that usually decide the choice: providers, platforms, privacy model, pricing, and daily workflow.

We try to be specific. If another client is better for a certain kind of user, we say so. If Epistles is the better fit, we explain why and name the tradeoff. No email client is best for every inbox. A single-provider Gmail user on a Mac has different needs from someone juggling Gmail, Microsoft 365, Fastmail, another JMAP server, iCloud, Proton Mail, and IMAP across desktop, mobile, web, and a watch.

The short version: Epistles is built for people who want one local-first client for Gmail, Microsoft 365, Fastmail, JMAP-compatible servers, Proton Mail, Apple Mail / iCloud, and standard IMAP accounts, without giving up native provider behavior. It runs on macOS, Linux, Windows, iOS, Android, and the web, with triage apps for Apple Watch and Wear OS. Credentials sync through a zero-knowledge vault; mail content stays with your devices and providers.

Email client alternatives

Start here if you are comparing Epistles with another app: Newton Mail, Mimestream, Spark, Superhuman, Canary Mail, Thunderbird, Mailbird, or Apple Mail.

Epistles vs Newton Mail: Newton was the unified, keyboard-aware, multi-account client many power users still miss. Our comparison looks at what Newton got right, where Epistles follows the same philosophy, and where it goes further: local-first storage, zero-knowledge credential sync, Linux support, modern mobile apps, and watch triage. It is a good starting point if you are looking for a Newton Mail replacement in 2026.
Epistles vs Mimestream: Mimestream is an excellent Gmail client for Mac. If your email life is entirely Gmail and macOS, it may be the cleanest answer. Epistles is for a broader setup: Gmail plus Microsoft 365, Fastmail, Proton Mail, Apple Mail / iCloud, and IMAP, across desktop, mobile, web, Apple Watch, and Wear OS. Both can use Gmail’s native API. The difference is scope.
Epistles vs Spark Mail: Spark is strong if you want team email features such as shared drafts and comments. Epistles takes a different path: local-first storage, provider native behavior, and a zero-knowledge vault for credentials. Spark has an Apple Watch app; Epistles supports both Apple Watch and Wear OS, so Pixel Watch and Galaxy Watch users get wrist triage too. Choose Spark for team collaboration. Choose Epistles if provider coverage, local storage, or Wear OS support matters more.
Epistles vs Superhuman: Superhuman is built around speed, onboarding, keyboard shortcuts, and AI features. Epistles is much less expensive and is aimed at users who need more provider and platform coverage: Linux, Android, Fastmail, Proton Mail, IMAP, and watch triage. If concierge onboarding and AI workflows are the reason you are shopping, Superhuman may be the better fit. If you want a quieter, local-first client for more accounts, compare the two.
Epistles vs Canary Mail: Canary Mail leans into AI summaries, writing assistance, and multi-account convenience. Epistles does not send your mail to a model provider and does not use AI features as part of the product. That is a deliberate tradeoff: local-first storage and zero-knowledge credential sync set a tighter boundary. If AI assistance is the main requirement, Canary is worth a look. If the privacy model matters more, compare it with Epistles.
Epistles vs Thunderbird: Thunderbird is open source, long-lived, cross-platform, and excellent on Linux. Epistles is not open source, so that may settle the decision for some people. The reason to compare them anyway is protocol depth and device coverage: Gmail API, OWA for Microsoft 365, JMAP for Fastmail and compatible servers, Proton support without Bridge, iCloud mail/calendar/contact setup, iOS, Apple Watch, Wear OS, and zero-knowledge credential sync.
Epistles vs Mailbird: Mailbird is a polished Windows-first email client with app integrations built into the mail window. Epistles is cross-platform in a different way: macOS, Linux, Windows, iOS, Android, web, Apple Watch, and Wear OS, with provider-native mail support and a zero-knowledge vault. If you want a Windows productivity hub, Mailbird is relevant. If your inbox needs to move cleanly across every device, compare it with Epistles.
Epistles vs Apple Mail: Apple Mail is free, built in, and good for a simple iCloud or Gmail setup on Apple devices. Epistles is for people whose mail spans Apple and non-Apple worlds: Microsoft 365 via OWA, Fastmail and compatible JMAP servers via JMAP, Proton Mail without Bridge, standard IMAP, Linux, Windows, Android, and Wear OS. It also sets up iCloud mail, calendar, and contacts together instead of scattering them through system settings.

Provider guides

These pages answer a different question: not “which email app is better?” but “how well does Epistles handle this provider?” They are useful if Gmail, Microsoft 365, Fastmail, another JMAP server, or Proton Mail is the account you care about most.

Use Gmail in Epistles: Epistles connects to Gmail with Gmail’s native API rather than flattening the account through IMAP. Labels stay labels, categories stay categories, server-side filters remain visible, and aliases behave the way Gmail users expect. The difference is that your Outlook, Fastmail, JMAP-powered server, Proton Mail, iCloud, and IMAP accounts can sit beside Gmail in the same client.
Use Microsoft 365 in Epistles: Epistles connects to Microsoft 365 through OWA instead of relying on older Exchange paths. That keeps Microsoft categories, mailbox behavior, and push closer to the account’s native model, while still letting Microsoft mail live beside Gmail, Fastmail, JMAP servers, Proton Mail, iCloud, and IMAP.
Use Fastmail in Epistles: Fastmail is one of the best homes for standards-based mail, and JMAP is the protocol that makes it feel modern. Epistles speaks JMAP directly, so Fastmail and any compatible JMAP server can keep their native behavior while sharing one client with your other accounts.
Use Proton Mail in Epistles, no Bridge: Epistles supports Proton Mail directly, without Proton Bridge. It decrypts on-device, keeps Proton private keys in the operating system keychain, and deliberately excludes those keys from Cloud Vault. Read this page if you want Proton Mail in a third-party client on desktop, mobile, and web without adding a local Bridge process.

Other clients people ask about

Some products are important to the email landscape even if they do not need a full page yet. Here is the short version.

Epistles vs HEY: HEY is a full workflow reset: new address, Screener, Imbox, Feed, Paper Trail, and a very specific way to think about mail. Epistles is for the opposite situation: you want to keep your existing Gmail, Fastmail, Microsoft 365, iCloud, Proton Mail, and IMAP accounts, but manage them from one calm client.
Epistles vs Airmail: Airmail has deep Mac integration and a flexible plugin system. Epistles does not try to recreate that plugin model. The tradeoff is a wider platform target, local-first storage, provider-native behavior, and support for Linux, Android, web, Apple Watch, and Wear OS alongside Mac and iOS.
Epistles vs Spike: Spike turns email into a chat-style conversation timeline. Epistles keeps email shaped like email: subjects, threads, signatures, attachments, and a writing surface that treats a long message as a long message.

Why some clients are not listed

A comparison page should help someone make a decision. These products may be worth mentioning, but a full page would either duplicate another comparison or overstate the overlap.

Outlook (the client itself, on Mac and Windows). Most people asking about Outlook are really asking about Microsoft 365 as a provider. The Microsoft 365 guide covers that better than a separate page about the Outlook app would.
Inbox by Google. Google retired it in 2019. People still search for replacements, but the Newton Mail comparison covers the same desire for a calmer, smarter unified inbox more directly.
Mailspring. Mailspring is open source and cross-platform, and the audience overlap is real. It is not high enough yet to justify a dedicated comparison page, but it belongs in the broader conversation around desktop email clients.
Edison Mail. Edison’s public history around inbox data monetization makes the privacy comparison too obvious to be useful as a standalone page.
Polymail. The product has been quiet for long enough that we would rather wait for a clearer signal before writing a current comparison.

Suggest another comparison

If the email client you are weighing is not on this page, write to us at support@epistles.com and tell us which one and why. The list will change as readers ask for more specific comparisons.

If you already know what you need, Epistles is for people who want Gmail, Microsoft 365, Fastmail, JMAP-compatible servers, Proton Mail, Apple Mail / iCloud, and IMAP in one local-first client across desktop, mobile, web, Apple Watch, and Wear OS. Start at epistles.com or join the waitlist below.