eM Client vs Thunderbird
Both replace Mimestream, Spark Premium and Superhuman.
| Fact |  eM ClientMail, calendar and contacts client whose one-time licence covers future versions |  ThunderbirdFree mail, calendar and contacts with no tier above it |
|---|---|---|
| Price | €39.95 | Free |
| Licence | PerpetualUpdates included, forever | Open sourceNothing to buy; source published |
| The catch | VIP Support is free for the first year only, then needs a paid extension | Nothing to pay, but it is a cross-platform app that never quite feels Mac-native |
| Against a subscription | Replaces Mimestream$50 a year. No payback figure, because we don't convert currencies. | Replaces Mimestream$50 a year |
| Seats | 3 MacsOne user, up to 3 devices; Business licences are counted per device instead. | not established |
| Developer account | None needed | None needed |
| Works offline | Partly | Partly |
| Apple Silicon | Intel only | Native |
| Free trial | Yes | does not apply |
| On Setapp | No | No |
| Buy direct | Get it |
Both prices read 22 Sep 2026, on the pages these buttons open. Minimum macOS and App Store rating are not established for either app, so those rows are left out.
In their own right
eM Client
A desktop mail client that also does calendar, contacts, tasks and chat, with PGP and S/MIME built in. The one-time Personal licence includes Lifetime Upgrades, so it stays valid for future major versions rather than only the one you installed.
Thunderbird
The open-source desktop mail client, with a calendar, an address book and OpenPGP encryption built in. Free forever on the desktop, funded by donations rather than seats.