Furthermore, there are add-ons for extending Thunderbird features.

Customization: Thunderbird supports skins for changing the look & feel.

Large File Management: Upload large attachments to outside storage providers without leaving Thunderbird.

Junk Mail Filter: Thunderbird has its spam filter.

Search & Filter: Efficient search and quick filter tools for your emails as well as the web.

Privacy & Security: Robust privacy options and phishing protection.

Smart Folder: Combined email folders for multiple accounts.

Activity Manager: Recorded interactions between the email provider and Thunderbird.

And, includes CardDAV address book support.

Contacts Management: Includes an address book that can store detailed information about your contacts.

The user interface hasn’t changed much over the years but received some revamps with Thunderbird 91 and later versions, but it is a no-nonsense email client with all the essential features. You can also find it pre-installed on several Linux distributions. Thunderbird is one of the most popular and oldest open-source email clients from Mozilla Foundation. They are listed here because they are available on Linux and the article’s focus is on Linux.

Some applications mentioned here are not open source.

Mozilla thunderbird vs outlook reddit