
Thunderbird
Mozilla's free, open-source desktop mail client.
The app you read your mail in is as important as who hosts it. A good client can block tracking pixels, strip dangerous HTML, and layer end-to-end encryption on top of any mailbox, while a careless one leaks your IP address and reading habits to every sender. The trade-off is usually convenience: the most private clients ask for more setup and encryption only works when the person you write to supports it too.
An email client is separate from your email provider and switching clients is painless so pick one that adds privacy rather than stripping it away. Prioritise open-source apps that block trackers by default and support OpenPGP or S/MIME, then weigh how much setup you are willing to do against how polished you want the experience to feel. On mobile, a client that avoids Google's push infrastructure keeps more of your metadata out of third-party hands. Remember that even the best client cannot make a snooping provider private so pair a strong client with a trustworthy mailbox.
Here are some things to look for.

Mozilla's free, open-source desktop mail client.

Feature-enhanced Thunderbird fork with no telemetry

Privacy-obsessed open-source email for Android.

Veteran open-source Android client, now part of Thunderbird.

Polished paid client with built-in PGP encryption.

Full mail and calendar suite for the Linux desktop.

KDE's integrated mail and groupware suite for Linux.

Keyboard-driven terminal email client for power users.

Lightweight, fast GTK email client with strong PGP support